Question

我试图在全屏幕ImageView中显示图像。除了零，我一直得到一个例外。如何获得ImageView的宽度和高度，以便我可以缩放图像？

如果我对尺寸进行硬编码，一切都按预期工作。

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.Log;
import android.widget.ImageView;
import android.widget.Toast;

public class SingleImageActivity extends Activity{
    private ImageView mFullPageImage;
    private static final String SELECTED_FILEPATH = "msd.com.example.dailyselfie.selected_filepath";
    private String filepath;
    int targetW;
    int targetH;



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.single_image_activity);

        mFullPageImage = (ImageView) findViewById(R.id.fullPageImageView);


        filepath = getIntent().getExtras().getString(SELECTED_FILEPATH);

        processPicture(filepath);

        //Toast.makeText(this, filename, Toast.LENGTH_SHORT);

    }

    @Override
     public void onWindowFocusChanged(boolean hasFocus) {
         targetW = mFullPageImage.getWidth();
         targetH = mFullPageImage.getHeight();


     }

    protected void processPicture(String filepath){
        //targetW = mFullPageImage.getWidth();
        //targetH = mFullPageImage.getHeight();
        //targetW = 400;
        //targetH = 400;


        // Get the dimensions of the bitmap
        BitmapFactory.Options bmOptions = new BitmapFactory.Options();
        bmOptions.inJustDecodeBounds = true;
        BitmapFactory.decodeFile(filepath, bmOptions);
        int photoW = bmOptions.outWidth;
        int photoH = bmOptions.outHeight;

        // Determine how much to scale down the image
        int scaleFactor = Math.min(photoW/targetW, photoH/targetH);

        // Decode the image file into a Bitmap sized to fill the View
        bmOptions.inJustDecodeBounds = false;
        bmOptions.inSampleSize = scaleFactor;
        bmOptions.inPurgeable = true;

        Bitmap bitmap = BitmapFactory.decodeFile(filepath, bmOptions);
        //display with no options
        //Bitmap bitmap = BitmapFactory.decodeFile(filepath);
        mFullPageImage.setImageBitmap(bitmap);
    }
}

Answer 1

如果您尝试全屏设置位图，可以使用下面的代码来获取屏幕的宽度和高度。

WindowManager wm = (WindowManager) mContext
            .getSystemService(Context.WINDOW_SERVICE);
    Display display = wm.getDefaultDisplay();
    Point size = new Point();
    display.getSize(size);
    int width=size.x;
    int height= size.y;

Answer 2

您收到divide by zero exception，因为targetW和targetH的值为零。在这一行中，您试图将值除以零

int scaleFactor = Math.min(photoW/targetW, photoH/targetH);

如果您在Android完成在屏幕上绘制它之前在任何视图上调用getHeight或getWidth方法，它将返回零。

所以请使用ViewTreeObserver

聆听完成视图的绘制

我想要问的另一件事是你是在尝试保持图像的宽高比，或者如果图像被拉伸你就可以了。

尝试在全屏ImageView中显示位图

2 个答案: