Question

In my custom views OnDraw method I draw a Bitmap to the center of the Canvas with

protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    Rect r = canvas.getClipBounds();
    displayWidth = r.right;
    displayHeight = r.bottom;
    camera.applyToCanvas(canvas);
    float zW = (float)bitmapWidth / (float)displayWidth;
    float zH = (float)bitmapHeight / (float)displayHeight;
    float z = 0.0f;
    if (zW>1 || zH>1) {
        z = Math.max(zW, zH); 
    }
    canvas.drawColor(Color.DKGRAY);
    canvas.drawBitmap(bitmap, (displayWidth/2.0f - (bitmapWidth)/2.0f), (displayHeight/2.0f - bitmapHeight/2.0f), paint);
    if (z>0) {
        camera.translate(z, -z, z);
    }
}

If the Bitmap is larger in height or width is larger then Canvas size (displayWidth, displayHeight), how can I use the Camera class to autozoom to fit the Bitmap and center it to the Canvas. Any ideas?

Answer 1

Try to create a Matrix instance and initialize it using

public boolean setRectToRect (RectF src, RectF dst, Matrix.ScaleToFit stf)

You need to do this only once and keep the matrix in memory. Note that Matrix.ScaleToFit define the CENTER value.

Later when you draw the bitmap use this version of the drawBitmap:

public void drawBitmap (Bitmap bitmap, Matrix matrix, Paint paint)