Question

我必须在地图视图上放置标记并在标记上写一个数字。我已经这样做了，但文本对齐方式因不同分辨率而异。下面是参考代码

        float xVal = (float) curScreenCoords.x;  // Point curScreenCoords
        float yVal = (float) curScreenCoords.y-20; // Point curScreenCoords
        Bitmap bitmap = BitmapFactory.decodeResource ( context.getResources() , ( R.drawable.pin_number ) ) ;
        canvas.drawBitmap(bitmap, xVal, yVal, getInnerPaint()); 

        public Paint getInnerPaint() {
         if (innerPaint == null) {
             innerPaint = new Paint();
         }
        innerPaint.setARGB(255, 117, 161, 220); // blue
        innerPaint.setAntiAlias(true);  
        innerPaint.setStyle(Style.FILL);
        return innerPaint;
        }
        canvas.drawText(String.valueOf(10), xVal+20, yVal+22, getCountPaint()); // 10 is just for example, it can vary to one digit to two to three 
        public Paint getCountPaint() {
        if (innerPaint == null) {
        innerPaint = new Paint();
        }
        innerPaint.setARGB(255, 255, 255, 255); 
        innerPaint.setAntiAlias(true);  
        innerPaint.setStyle(Style.FILL);
        innerPaint.setTextSize(12f);
        innerPaint.setTextAlign(Align.CENTER);
        return innerPaint;
       }

一切正常，除了文本对齐，此代码适用于480 * 800分辨率。文本在画布中完全居中对齐。 x，y位置在图像上是完美的，但在320 * 480上看起来并不完美。文本的x和y位置在此分辨率上看起来不同。任何人都可以建议我究竟发生了什么错误？在不同尺寸的设备上做同样的事情还有什么基础吗？提前致谢。

Answer 1

我认为您可以测量文本在画布中写入后的宽度和高度，然后使用它来居中。类似的东西：

String text = "whatever";
Rect bounds = new Rect();
paint.getTextBounds(text, 0, text.length(), bounds);
canvas.drawText(text, (canvas.getWidth() - bounds.width()) / 2, (canvas.getHeight() - bounds.height()) / 2, paint);

Answer 2

嗨，我猜上面给出的答案都不够好，所以我发布我的答案试试看，所有设备上的人都会工作，而且根本不复杂

Canvas canvas = new Canvas(bitmap);

Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
//paint.setTextAlign(Align.CENTER);
paint.setColor(activity.getResources().getColor(R.color.white));
paint.setTextSize(30);

// draw text to the Canvas center
Rect boundsText = new Rect();
paint.getTextBounds(String.valueOf(cluster.getMarkerList().size()), 0, 
    String.valueOf(cluster.getMarkerList().size()).length(), boundsText);
int x = (bitmap.getWidth() - boundsText.width()) / 2;
int y = (bitmap.getHeight() + boundsText.height()) / 2;

canvas.drawText(String.valueOf(cluster.getMarkerList().size()), x, y, paint);

Answer 3

您的值curScreenCoords.y-20和xVal+20, yVal+22对所有分辨率都有恒定的像素偏移量，但它们应该取决于设备的像素密度，如下所示：

xOffset = (int) (13.33f * context.getResources().getDisplayMetrics().density + 0.5f);
yOffset = (int) (14.67f * context.getResources().getDisplayMetrics().density + 0.5f);
canvas.drawText(String.valueOf(10), xVal + xOffset, yVal + yOffset, getCountPaint());

Answer 4

确保检查硬件加速是否已关闭。在4.1.2和其他设备（三星Galaxy Tag 2.0）上，您会收到致命信号11错误。

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB)
{
    setLayerType(View.LAYER_TYPE_SOFTWARE, null);
}

这解决了我使用此代码时遇到的问题。 canvas.drawText导致错误。

Answer 5

您可以扩展Image类并覆盖它的onDraw。如下

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.ColorFilter;
import android.graphics.Paint;
import android.widget.ImageView;

/**
 * @author amit
 * 
 */
public class CustomImageView extends ImageView {
    private int notificationCount;
    private Paint paint;

    /**
     * @param context
     */
    public CustomImageView(Context context) {
        super(context);
        notificationCount = 0;
        paint = new Paint();
        paint.setColor(Color.RED);
        ColorFilter cf = new ColorFilter();
        paint.setColorFilter(cf);
        paint.setStyle(Paint.Style.FILL);
        paint.setFakeBoldText(true);
        paint.setTextSize(15);
    }

    public synchronized void incrementNotification() {
        notificationCount--;
        this.invalidate();
    }

    public synchronized void decrementNotification() {
        notificationCount++;
        this.invalidate();
    }

    /**
     * @return the notificationCount
     */
    public synchronized int getNotificationCount() {
        return notificationCount;
    }

    /**
     * @param notificationCount
     *            the notificationCount to set
     */
    public synchronized void setNotificationCount(int notificationCount) {
        this.notificationCount = notificationCount;
        this.invalidate();
    }

    /*
     * (non-Javadoc)
     * 
     * @see android.widget.ImageView#onDraw(android.graphics.Canvas)
     */
    @Override
    protected void onDraw(Canvas canvas) {
        // System.out.println("OnDraw is called");
        super.onDraw(canvas);
        if (notificationCount == 0) {
            return;
        }
        canvas.drawText(String.valueOf(notificationCount), 0, 0, paint);
    }

}

比你可以调用以下任何一种方法

incrementNotification(); 
decrementNotification();
setNotification(int number);

在构造函数中选择您选择的颜色。祝您好运！

Answer 6

我有同样的问题。我想在位图中绘制文本 - 用于在Google地图上进行聚类。实际上它在位图的CENTER上绘制文本。

用Kotlin编写的代码

public string Authenticate(LoginDetails loginDetails)
        {
            SecureString securePassword = new SecureString();
            foreach (var c in loginDetails.Password)
            {
                securePassword.AppendChar(c);
            }
            SharePointOnlineCredentials credentials = new SharePointOnlineCredentials(loginDetails.UserName, securePassword);
            return credentials.GetAuthenticationCookie(new Uri(loginDetails.SiteUrl));
        }

在图像android中画一个文本

6 个答案: