更新 - 没有“操纵数据缓冲区”

Question

我有两个BufferedImages：一个是TYPE_INT_ARGB，另一个是TYPE_BYTE_GRAY。如何使用仅使用API替换灰度图像的整个彩色图像的alpha波段，而不会干扰RGB值？

class TrackingAdapter(var list: MutableList<TrackingModel>, var context: Context) :
    RecyclerView.Adapter<TrackingAdapter.viewHolder>() {

private var onclick : onItemClick? = null

override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int): viewHolder {
    val binding : ItemTrackingDataBinding = DataBindingUtil.inflate(
            LayoutInflater.from(context),R.layout.item_tracking_data,parent,false)
    return viewHolder(binding)
}

override fun onBindViewHolder(holder: viewHolder?, position: Int) {
    val model = list[position]
    holder!!.bind(model)
}

override fun getItemCount(): Int = list.size

inner class viewHolder(private var binding: ItemTrackingDataBinding) : RecyclerView.ViewHolder(binding.root){

    init {
        binding.vLayoutTracking.setOnClickListener({
            val position = adapterPosition
            onclick!!.onClickItem(list[position])
        })
    }

    fun bind(model: TrackingModel){
        binding.vName.text = model.nama
        binding.vNoapp.text = model.no_kontrak
        binding.vNomsn.text = model.no_mesin
        binding.vNopol.text = model.no_polisi
        binding.vStatus.text = model.status
        binding.executePendingBindings()
    }
}

fun setOnClick (onItemClick: onItemClick){
    this.onclick = onItemClick
}

interface onItemClick{
    fun onClickItem(model: TrackingModel)
}

我可以通过屏蔽和复制字节来手动完成：

override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int): viewHolder {
    val binding : ItemTrackingDataBinding = DataBindingUtil.inflate(
            LayoutInflater.from(context),R.layout.item_tracking_data,parent,false)
    return viewHolder(binding)
}

然而，API方式是什么？

更新＃1 样本图像：输入灰度alpha，输入颜色cat和带孔的输出颜色cat。

生成的图像在输出颜色的alpha中具有灰度。在照片编辑器中查看生成的图像，您将看到中间的孔实际上是透明的。

final int width = 200;
final int height = 200;

final BufferedImage colorImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
final BufferedImage grayscaleImg = new BufferedImage(width, height, BufferedImage.TYPE_BYTE_GRAY);
Graphics2D g = colorImg.createGraphics();
// flip some mystical switches
// g.drawImage( grayscaleImg into colorImg's alpha band )
g.dispose();

为了重申我的原始目标，Java API实现上述代码的方式是什么？

Answer 1

啊，你想用面具剪掉一部分图像，不好。

简单的解决方案 - 使用基于alpha的掩码开始。但我认为你没有这个选择。我确实尝试过找到一个可能做到这一点的解决方案，而是偶然发现了this example。

哪个能够产生你似乎正在寻找的结果

（蓝色是面板的背景颜色）

核心功能来做......

public void applyGrayscaleMaskToAlpha(BufferedImage image, BufferedImage mask) {
    int width = image.getWidth();
    int height = image.getHeight();

    int[] imagePixels = image.getRGB(0, 0, width, height, null, 0, width);
    int[] maskPixels = mask.getRGB(0, 0, width, height, null, 0, width);

    for (int i = 0; i < imagePixels.length; i++) {
        int color = imagePixels[i] & 0x00ffffff; // Mask preexisting alpha
        int alpha = maskPixels[i] << 24; // Shift blue to alpha
        imagePixels[i] = color | alpha;
    }

    image.setRGB(0, 0, width, height, imagePixels, 0, width);
}

但作为一个简单的可运行的例子......

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;

public class Test {

    public static void main(String[] args) {
        new Test();
    }

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (Exception ex) {
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public void applyGrayscaleMaskToAlpha(BufferedImage image, BufferedImage mask) {
        int width = image.getWidth();
        int height = image.getHeight();

        int[] imagePixels = image.getRGB(0, 0, width, height, null, 0, width);
        int[] maskPixels = mask.getRGB(0, 0, width, height, null, 0, width);

        for (int i = 0; i < imagePixels.length; i++) {
            int color = imagePixels[i] & 0x00ffffff; // Mask preexisting alpha
            int alpha = maskPixels[i] << 24; // Shift blue to alpha
            imagePixels[i] = color | alpha;
        }

        image.setRGB(0, 0, width, height, imagePixels, 0, width);
    }

    public class TestPane extends JPanel {

        private BufferedImage master;
        private BufferedImage mask;

        public TestPane() {
            setBackground(Color.BLUE);
            try {
                master = ImageIO.read(new File("..."));
                mask = ImageIO.read(new File("..."));

                applyGrayscaleMaskToAlpha(master, mask);
            } catch (IOException exp) {
                exp.printStackTrace();
            }
        }

        @Override
        public Dimension getPreferredSize() {
            Dimension size = super.getPreferredSize();
            if (master != null && mask != null) {
                size = new Dimension(master.getWidth() + mask.getWidth(), Math.max(master.getHeight(), mask.getHeight()));
            }
            return size;
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            int x = (getWidth() - (master.getWidth() + mask.getWidth())) / 2;
            int y = (getHeight() - master.getHeight()) / 2;
            g.drawImage(master, x, y, this);

            x += mask.getWidth();
            y = (getHeight() - mask.getHeight()) / 2;
            g.drawImage(mask, x, y, this);
        }

    }

}

对不起有困惑

更新 - 没有“操纵数据缓冲区”

我一直在寻找Java API的方式来完成相同的工作而不需要操作位

好的，所以我也更喜欢一种从灰度图像生成基于alpha的图像的解决方案，它更适合整个Graphics 2D API。所以，经过一点阅读of this question which keeps on giving后，我偶然发现了这个想法......

public static BufferedImage grayScaleToTransparency(BufferedImage master) {
    ImageFilter filter = new RGBImageFilter() {
        public final int filterRGB(int x, int y, int rgb) {
            return (rgb << 16) & 0xFF000000;
        }
    };

    ImageProducer ip = new FilteredImageSource(master.getSource(), filter);
    Image img = Toolkit.getDefaultToolkit().createImage(ip);

    BufferedImage buffer = createCompatibleImage(img.getWidth(null), img.getHeight(null), Transparency.TRANSLUCENT);
    Graphics2D g2d = buffer.createGraphics();
    g2d.drawImage(img, 0, 0, null);
    g2d.dispose();

    return buffer;
}

现在，使用BufferedImageFilter和BufferedImageOp可能会有所收获，但我没有时间或经验对其进行进一步调查。

使用这种技术我能够产生......

原始图片|原始（灰度）面具|基于Alpha的面具|蒙面图像

同样，蓝色是面板的背景颜色。

import java.awt.AlphaComposite;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsEnvironment;
import java.awt.Image;
import java.awt.RenderingHints;
import java.awt.Toolkit;
import java.awt.Transparency;
import java.awt.image.BufferedImage;
import java.awt.image.FilteredImageSource;
import java.awt.image.ImageFilter;
import java.awt.image.ImageProducer;
import java.awt.image.RGBImageFilter;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;

public class Test {

    public static void main(String[] args) {
        new Test();
    }

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (Exception ex) {
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public static GraphicsConfiguration getGraphicsConfiguration() {
        return GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice().getDefaultConfiguration();
    }

    public static BufferedImage createCompatibleImage(int width, int height, int transparency) {
        BufferedImage image = getGraphicsConfiguration().createCompatibleImage(width, height, transparency);
        image.coerceData(true);
        return image;
    }

    public static void applyQualityRenderingHints(Graphics2D g2d) {
        g2d.setRenderingHint(RenderingHints.KEY_ALPHA_INTERPOLATION, RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY);
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        g2d.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY);
        g2d.setRenderingHint(RenderingHints.KEY_DITHERING, RenderingHints.VALUE_DITHER_ENABLE);
        g2d.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON);
        g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
        g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
        g2d.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_PURE);
    }

    public static BufferedImage applyMask(BufferedImage master, BufferedImage mask) {
        int imgWidth = master.getWidth();
        int imgHeight = master.getHeight();

        BufferedImage imgMask = createCompatibleImage(imgWidth, imgHeight, Transparency.TRANSLUCENT);
        Graphics2D g2 = imgMask.createGraphics();
        applyQualityRenderingHints(g2);

        g2.drawImage(mask, 0, 0, null);
        g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_IN, 1f));
        g2.drawImage(master, 0, 0, null);
        g2.dispose();

        return imgMask;
    }

    public static BufferedImage grayScaleToTransparency(BufferedImage master) {
        ImageFilter filter = new RGBImageFilter() {
            public final int filterRGB(int x, int y, int rgb) {
                return (rgb << 16) & 0xFF000000;
            }
        };

        ImageProducer ip = new FilteredImageSource(master.getSource(), filter);
        Image img = Toolkit.getDefaultToolkit().createImage(ip);

        BufferedImage buffer = createCompatibleImage(img.getWidth(null), img.getHeight(null), Transparency.TRANSLUCENT);
        Graphics2D g2d = buffer.createGraphics();
        g2d.drawImage(img, 0, 0, null);
        g2d.dispose();

        return buffer;
    }

    public class TestPane extends JPanel {

        private BufferedImage master;
        private BufferedImage originalMask;
        private BufferedImage alphaMask;
        private BufferedImage masked;

        public TestPane() {
            setBackground(Color.BLUE);
            try {
                master = ImageIO.read(new File("/Users/swhitehead/Downloads/lIceL.png"));
                originalMask = ImageIO.read(new File("/Users/swhitehead/Downloads/MXmFp.png"));
                alphaMask = grayScaleToTransparency(originalMask);
                masked = applyMask(master, alphaMask);
//                tinted = tint(master, mask);
            } catch (IOException exp) {
                exp.printStackTrace();
            }
        }

        protected int desiredWidth() {
            return master.getWidth() + originalMask.getWidth() + alphaMask.getWidth() + masked.getWidth();
        }

        protected int desiredHeight() {
            return Math.max(Math.max(Math.max(master.getHeight(), originalMask.getHeight()), alphaMask.getHeight()), masked.getHeight());
        }

        @Override
        public Dimension getPreferredSize() {
            Dimension size = super.getPreferredSize();
            if (master != null && originalMask != null) {
                size = new Dimension(desiredWidth(),
                        desiredHeight());
            }
            return size;
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            int x = (getWidth() - desiredWidth()) / 2;
            int y = (getHeight() - master.getHeight()) / 2;
            g.drawImage(master, x, y, this);

            x += originalMask.getWidth();
            y = (getHeight() - originalMask.getHeight()) / 2;
            g.drawImage(originalMask, x, y, this);

            x += alphaMask.getWidth();
            y = (getHeight() - alphaMask.getHeight()) / 2;
            g.drawImage(alphaMask, x, y, this);

            x += masked.getWidth();
            y = (getHeight() - masked.getHeight()) / 2;
            g.drawImage(masked, x, y, this);
        }

    }

}

Answer 2

我感谢@Hovercraft Full Of Eels建议BufferedImageOp，这导致BandCombineOp。当用合适的矩阵进行馈送时，该类可以操纵任何或所有频带。减轻，变暗，移动和复制波段，而无需访问DataBuffer或操作位。

如何将图像放入alpha波段

加载或绘制图像;这将成为阿尔法乐队。图片可以是彩色或灰度。
将图片转换为BufferedImage.TYPE_BYTE_GRAY
将灰度转换为BufferedImage.TYPE_INT_ARGB。颜色 band将包含 near 相同的灰度副本。
使用BandCombineOp将色带复制到Alpha波段。有关矩阵，请参阅toAlpha()。

这是在编码位操作上移动/复制波段的更好方法，因为它在数学上更优雅，并且API可以利用视频加速硬件（如果存在并由Java支持。）

示例Java应用程序：嵌入alpha

包含一个应用程序来演示该过程。选择颜色源和alpha源，应用程序将它们合成为一个图像。显示两个源图像，中间图像和复合图像以保持理智。右键单击要保存的任何图像。

颜色来源：猫

阿尔法来源：鸟

Alpha源：绿色波段复制到alpha波段

组合

运行应用程序：（1）创建名为embedalpha的JavaFX项目，（2）删除自动生成的.java文件的内容，（3）粘贴我的代码，以及（4）运行。

要跟踪过程，请在方法handleBuildComposite()中添加断点。忽略appendGallery()。乐队副本toAlpha()。

/*
Your use of any portion of the code constitutes your acceptance of full
responsibility for all wonderful and aweful outcomes.
 */
package embedalpha;

import java.awt.AlphaComposite;
import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.Toolkit;
import java.awt.color.ColorSpace;
import java.awt.color.ICC_ColorSpace;
import java.awt.color.ICC_Profile;
import java.awt.image.BandCombineOp;
import java.awt.image.BufferedImage;
import java.awt.image.ColorConvertOp;
import java.io.File;
import javafx.application.Application;
import javafx.beans.property.IntegerProperty;
import javafx.beans.property.ObjectProperty;
import javafx.beans.property.SimpleIntegerProperty;
import javafx.beans.property.SimpleObjectProperty;
import javafx.collections.ListChangeListener;
import javafx.collections.ObservableList;
import javafx.embed.swing.SwingFXUtils;
import javafx.event.ActionEvent;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.control.Alert;
import javafx.scene.control.Button;
import javafx.scene.control.ButtonType;
import javafx.scene.control.ScrollPane;
import javafx.scene.control.Tooltip;
import javafx.scene.image.Image;
import javafx.scene.image.WritableImage;
import javafx.scene.input.MouseButton;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.FlowPane;
import javafx.scene.layout.HBox;
import javafx.scene.paint.Color;
import javafx.scene.paint.ImagePattern;
import javafx.scene.paint.Paint;
import javafx.stage.FileChooser;
import javafx.stage.Stage;
import javax.imageio.ImageIO;

/**
 * Demonstrate copying/moving a color band to the alpha band within the same
 * image using only API. The specific method is toAlpha().
 * 
 * @author deskwarrior
 * @see https://stackoverflow.com/questions/47446922/draw-grayscale-image-to-another-bufferedimages-alpha-band-using-api-only
 */
public class TheApp extends Application {
    private final int NODE_SPACING = 5;
    private final int TILE_SIZE = 40;
    private final int APP_WIDTH;
    private final int APP_HEIGHT;

    private final ObjectProperty<BufferedImage> colorSource = new SimpleObjectProperty<>(this, "colorSource", null);
    private final ObjectProperty<BufferedImage> alphaSource = new SimpleObjectProperty<>(this, "alphaSource", null);
    private final Paint backgroundColor;
    private final HBox gallery = new HBox(NODE_SPACING);
    private final IntegerProperty gallerySize = new SimpleIntegerProperty(this, "gallerySize", 0);
    private final Tooltip canvasTip = new Tooltip("Right-click to save image as PNG.");
    private Canvas colorSourceCanvas = null;
    private Canvas alphaSourceCanvas = null;

    private final FileChooser openFC = new FileChooser();
    private final FileChooser saveFC = new FileChooser();
    private File lastDirectoryVisited = null;

    private final RenderingHints colorHints = new RenderingHints(
            RenderingHints.KEY_COLOR_RENDERING, 
            RenderingHints.VALUE_COLOR_RENDER_QUALITY);
    private final ICC_ColorSpace grayColorSpace;
    private final ICC_ColorSpace rgbColorSpace;

    private final BorderPane root = new BorderPane();
    private Stage stage = null;


    public TheApp() {
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        APP_WIDTH = screenSize.width;
        APP_HEIGHT = screenSize.height * 2 / 3;

        openFC.getExtensionFilters().addAll(
            new FileChooser.ExtensionFilter("Image Files", "*.png", "*.jpg", "*.gif", "*.bmp"),
            new FileChooser.ExtensionFilter("All Files", "*.*"));

        saveFC.setTitle("Save image as PNG");
        saveFC.getExtensionFilters().addAll(
            new FileChooser.ExtensionFilter("Portable network graphics", "*.png"));

        colorHints.put(RenderingHints.KEY_DITHERING, RenderingHints.VALUE_DITHER_ENABLE);
        ICC_Profile grayProfile = ICC_Profile.getInstance(ColorSpace.CS_GRAY);
        grayColorSpace = new ICC_ColorSpace(grayProfile);
        ICC_Profile rgbProfile = ICC_Profile.getInstance(ColorSpace.CS_sRGB);
        rgbColorSpace = new ICC_ColorSpace(rgbProfile);

        Image tile = createCheckeredTile();
        backgroundColor = new ImagePattern(tile, 0, 0, TILE_SIZE, TILE_SIZE, false);
    }

    /**
     * Convert a BufferedImage to another color space.
     * 
     * @param src cannot be TYPE_CUSTOM or null
     * @param dstImageType valid BufferedImage types: TYPE_BYTE_GRAY, 
     * TYPE_INT_RGB, TYPE_INT_ARGB
     * @return BufferedImage in the new color space. never null.
     * @exception NullPointerException when src is null
     * @exception IllegalArgumentException when dstImageType is not one of the
     * three accepted types
     */
    private BufferedImage toImageType(BufferedImage src, int dstImageType) {
        BufferedImage dst;

        if(src.getType() == dstImageType)
            dst = src;

        else {
            ColorSpace dstColorSpace;

            switch(dstImageType) {
                case BufferedImage.TYPE_BYTE_GRAY:
                    dstColorSpace = grayColorSpace;
                    break;

                case BufferedImage.TYPE_INT_RGB:
                case BufferedImage.TYPE_INT_ARGB:
                    dstColorSpace = rgbColorSpace;
                    break;

                default:
                    String msg = String.format("Conversion to BufferedImage type %d not supported.", dstImageType);
                    throw new IllegalArgumentException(msg);
            }

            /*
            Using ColorConvertOp because the documentation promises images
            with pre-multiplied alphas will be divided out.

            Another possibility is dst.createGraphics().drawImage(src). Whether 
            drawImage() divides out premultiplied alphas is unknown to me, and  
            I don't feel like tracing the method to find out.
             */
            ColorSpace srcColorSpace = src.getColorModel().getColorSpace();
            ColorConvertOp op = new ColorConvertOp(srcColorSpace, dstColorSpace, colorHints);
            dst = new BufferedImage(src.getWidth(), src.getHeight(), dstImageType);
            op.filter(src, dst);
        }

        return dst;
    }

    /**
     * Starting point for merging color source and alpha source into one image.
     * 
     * @param e 
     */
    private void handleBuildComposite(ActionEvent e) {
        try {
            e.consume();

            /*
            Color source's RGB bands will become the composite's RGB bands.
            If color source is ARGB then discard the alpha band to remove
            any premultiplied alpha values.
            If color source is grayscale then convert to RGB in preparation
            for merge.
            */
            final BufferedImage colorSourceRGB = toImageType(getColorSource(), BufferedImage.TYPE_INT_RGB);
            appendGallery(colorSourceRGB, "Color source: RGB");

            /*
            One of alpha source's RGB bands will become the composite's alpha 
            band. 
            If alpha source is a color image, then convert to grayscale to get 
            R == G == B; at the expense of some information. If a color band 
            were copied to the alpha band without conversion, the resulting 
            alpha band wouldn't accurately represent the original color image 
            because R != G != B.
            If alpha source is a grayscale image then no change.
             */
            final BufferedImage alphaSourceGray = toImageType(getAlphaSource(), BufferedImage.TYPE_BYTE_GRAY);
            appendGallery(alphaSourceGray, "Alpha source: grayscale");

            /*
            The objective of this app is to copy/move a color band into the 
            alpha band. Problem is grayscales don't have an alpha band. Convert 
            to ARGB to give it one.
            */
            final BufferedImage alphaRGBA = toImageType(alphaSourceGray, BufferedImage.TYPE_INT_ARGB);
            appendGallery(alphaRGBA, "Alpha source: grayscale to RGBA");

            /*
            Method toAlpha() is where the magic happens. Copy/move one of the 
            color bands into the alpha band.
             */
            final BufferedImage trueAlpha = toAlpha(alphaRGBA);
            appendGallery(trueAlpha, "Alpha source: Green to Alpha, RGB to white");

            /*
            Composite the color values with the alpha values into one image.
            Copy colorSourceRGB's RGB into the composite's RGB. 
            Copy trueAlpha's alpha into the composite's alpha.
            */
            BufferedImage colorPlusAlpha = toComposite(colorSourceRGB, trueAlpha);
            appendGallery(colorPlusAlpha, "Color + alpha composite");
        }

        catch(Exception ex) {
            final Alert dlg = new Alert(Alert.AlertType.ERROR, ex.getMessage(), ButtonType.CLOSE);
            dlg.showAndWait();
        }
    }

    /**
     * Copy the green band into the alpha band.
     * 
     * @param src presumed to be some type with an alpha band. You're screwed
     * if it isn't.
     * @return a BufferedImage with the green band in the alpha band, and
     * the RGB bands set to white. Never null.
     */
    private BufferedImage toAlpha(BufferedImage src) {
        /*
        This matrix specifies which band(s) to manipulate and how. The 3-ones
        in the right-most column sets dst's RGB bands to white. The solitary
        one in the bottom row will copy the green band into dst's alpha band.

        Footnote: when the grayscale was converted to ARGB I expected the RGB
        bands to be identical. After some testing the bands were found to be
        *near* identical; it seems a color conversion from grayscale to 
        RGB is not as simple as a bulk memory copy. The differences are low 
        enough that no one would've noticed a difference had the either the 
        red or blue band been chosen over the green band.
        */
        final float[][] matrix = new float[][] {
            {0, 0, 0, 1},
            {0, 0, 0, 1},
            {0, 0, 0, 1},
            {0, 1, 0, 0}};

        BandCombineOp op = new BandCombineOp(matrix, null);
        BufferedImage dst = new BufferedImage(src.getWidth(), src.getHeight(), src.getType());
        op.filter(src.getRaster(), dst.getRaster());
        return dst;
    }

    /**
     * Composite color's RGB bands with alpha's alpha band into one image.
     * 
     * @param color anything except BufferedImage.TYPE_CUSTOM and null.
     * @param alpha anything with an alpha band otherwise very bad
     * @return a BufferedImage of the two inputs. never null.
     */
    private BufferedImage toComposite(BufferedImage color, BufferedImage alpha) {
        final int width = Math.max(color.getWidth(), alpha.getWidth());
        final int height = Math.max(color.getHeight(), alpha.getHeight());
        final BufferedImage dst = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
        Graphics2D g = dst.createGraphics();
        g.drawImage(color, null, 0, 0);

        /*
        AlphaComposite.DST_IN ignores alpha's RGB bands and copies just the
        alpha band.
        */
        g.setComposite(AlphaComposite.getInstance(AlphaComposite.DST_IN));
        g.drawImage(alpha, null, 0, 0);
        g.dispose();
        return dst;
    }

    private Image createCheckeredTile() {
        final Canvas can = new Canvas(TILE_SIZE, TILE_SIZE);
        final GraphicsContext gc = can.getGraphicsContext2D();
        final int haf = TILE_SIZE / 2;

        gc.setFill(Color.DARKGRAY);
        gc.fillRect(0, 0, haf, haf); // top-left
        gc.fillRect(haf, haf, haf, haf); // bottom-right


        gc.setFill(Color.DIMGREY);
        gc.fillRect(haf, 0, haf, haf); // top-right
        gc.fillRect(0, haf, haf, haf); // bottom-left

        WritableImage snapshot = can.snapshot(null, null);
        return snapshot;
    }

    private void loadImage(String title, ObjectProperty<BufferedImage> imageObj) {
        try {
            openFC.setTitle(title);
            openFC.setInitialDirectory(lastDirectoryVisited);
            File filePath = openFC.showOpenDialog(stage);
            if(filePath != null) {
                lastDirectoryVisited = filePath.getParentFile();
                BufferedImage image = ImageIO.read(filePath);
                imageObj.set(image);
            }
        }

        catch(Exception ex) {
            final Alert dlg = new Alert(Alert.AlertType.ERROR, ex.getMessage(), ButtonType.CLOSE);
            dlg.showAndWait();
        }
    }

    private void saveImage(MouseEvent e) {
        try {
            if(e.getButton() == MouseButton.SECONDARY) {
                e.consume();
                saveFC.setInitialDirectory(lastDirectoryVisited);
                File filePath = saveFC.showSaveDialog(stage);
                if(filePath != null) {
                    lastDirectoryVisited = filePath.getParentFile();
                    Canvas canvas = (Canvas) e.getSource();
                    BufferedImage img = (BufferedImage) canvas.getUserData();
                    ImageIO.write(img, "png", filePath);
                }
            }
        }

        catch(Exception ex) {
            final Alert dlg = new Alert(Alert.AlertType.ERROR, ex.getMessage(), ButtonType.CLOSE);
            dlg.showAndWait();
        }
    }

    private Canvas appendGallery(BufferedImage src, String desc) {
        final int width = src.getWidth();
        final int height = src.getHeight();
        final Canvas canvas = new Canvas(width, height);

        canvas.setUserData(src);
        Tooltip.install(canvas, canvasTip);
        canvas.setOnMouseReleased(this::saveImage);

        final GraphicsContext gc = canvas.getGraphicsContext2D();
        final Image image = SwingFXUtils.toFXImage(src, null);
        gc.setFill(backgroundColor);
        gc.fillRect(0, 0, width, height);
        gc.drawImage(image, 0, 0);

        String desc2 = desc != null && !desc.isEmpty() ? desc : "?";
        if(src.isAlphaPremultiplied())
            desc2 += ", premultiplied alpha";
        gc.setStroke(Color.LIME);
        gc.strokeText(desc2, 5, 20);

        gallery.getChildren().add(canvas);
        return canvas;
    }

    private boolean neitherColorNorAlpha(Node n) {
        boolean colorOrAlpha = 
            ((colorSourceCanvas != null) && (n == colorSourceCanvas)) ||
            ((alphaSourceCanvas != null) && (n == alphaSourceCanvas));
        return !colorOrAlpha;
    }

    private void setupMenu() {
        Button loadColorSource = new Button("Load color source ...");
        loadColorSource.setTooltip(new Tooltip("The image's color values will become the composite's color values."));
        loadColorSource.setOnAction((e) -> {
            e.consume();
            loadImage(loadColorSource.getText(), colorSource);
            colorSourceCanvas = appendGallery(getColorSource(), "Color source");
        });

        Button loadAlphaSource = new Button("Load alpha source ...");
        loadAlphaSource.setTooltip(new Tooltip("The image's color values will become the composite's alpha values."));
        loadAlphaSource.setOnAction((e) -> {
            e.consume();
            loadImage(loadAlphaSource.getText(), alphaSource);
            alphaSourceCanvas = appendGallery(getAlphaSource(), "Alpha source");
        });

        Button buildComposite = new Button("Build composite");
        buildComposite.setTooltip(new Tooltip("Merge color and alpha into one image."));
        buildComposite.setOnAction(this::handleBuildComposite);
        buildComposite.disableProperty().bind(colorSource.isNull().or(alphaSource.isNull()));

        Button clearGallery = new Button("Clear gallery");
        clearGallery.setTooltip(new Tooltip("Keep the current color source and alpha source; discard other images."));
        clearGallery.disableProperty().bind(gallerySize.lessThanOrEqualTo(2));
        clearGallery.setOnAction((e) -> {
            e.consume();
            gallery.getChildren().removeIf(this::neitherColorNorAlpha);
        });

        FlowPane parent = new FlowPane(NODE_SPACING, NODE_SPACING);
        parent.setAlignment(Pos.CENTER);
        parent.getChildren().addAll(loadColorSource, loadAlphaSource, buildComposite, clearGallery);
        parent.setPadding(new Insets(NODE_SPACING));
        root.setTop(parent);
    }

    private void setupGallery() {
        gallery.setPadding(new Insets(NODE_SPACING));
        ObservableList<Node> children = gallery.getChildren();
        children.addListener(new ListChangeListener<Node>() {
            @Override
            public void onChanged(ListChangeListener.Change c) {
                setGallerySize(children.size());
            }
        });
        ScrollPane scroll = new ScrollPane(gallery);
        scroll.setPannable(true);
        scroll.setStyle("-fx-background-color: transparent;");
        root.setCenter(scroll);
    }

    @Override
    public void start(Stage primaryStage) {
        stage = primaryStage;
        setupMenu();
        setupGallery();

        Scene scene = new Scene(root, APP_WIDTH, APP_HEIGHT);
        stage.setTitle("Embed alpha");
        stage.setScene(scene);
        stage.setResizable(true);
        stage.show();
    }

    public int getGallerySize() {
        return gallerySize.get();
    }

    public void setGallerySize(int value) {
        gallerySize.set(value);
    }

    public IntegerProperty gallerySizeProperty() {
        return gallerySize;
    }

    public BufferedImage getAlphaSource() {
        return alphaSource.get();
    }

    public void setAlphaSource(BufferedImage value) {
        alphaSource.set(value);
    }

    public ObjectProperty alphaSourceProperty() {
        return alphaSource;
    }

    public BufferedImage getColorSource() {
        return colorSource.get();
    }

    public void setColorSource(BufferedImage value) {
        colorSource.set(value);
    }

    public ObjectProperty colorSourceProperty() {
        return colorSource;
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        launch(args);
    }
}

仅使用API将灰度图像绘制到另一个BufferedImage的alpha波段

2 个答案:

更新 - 没有“操纵数据缓冲区”

如何将图像放入alpha波段

示例Java应用程序：嵌入alpha

仅使用API​​将灰度图像绘制到另一个BufferedImage的alpha波段

2 个答案:

更新 - 没有“操纵数据缓冲区”

如何将图像放入alpha波段

示例Java应用程序：嵌入alpha

仅使用API将灰度图像绘制到另一个BufferedImage的alpha波段