Android 缩放画布不起作用

Question

i'm trying to make a photo crop app and i want to load a large size image and scale it to to 480 Width and 800 Height (keep aspect ratio) but the problem is if i scale bitmap it shrinks image and when i save it the result get low quality so i decided to scale its canvas to keep bitmap original size. i need to keep original size but scale the image to fit in screen?

here is my code:

public void setBitmap(Bitmap bitmap) {

finalBitmap = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Bitmap.Config.ARGB_8888);
myCanvas = new Canvas(finalBitmap);
myCanvas.drawBitmap(bitmap, 0, 0, null);
myCanvas.scale(scaleFactor,scaleFactor);
isLoaded = true;
}

draw method:

protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);

    if (isLoaded)
        canvas.drawBitmap(finalBitmap, 0, 0, null);

}

i changed scalefactor with 0.9f ,480,... but non of them had effect on bitmap

Answer 1

Your code should look like this

canvas.save();
canvas.scale(mScaleFactor, mScaleFactor);
canvas.drawBitmap(bitmap, 0, 0, null);
canvas.restore();

Another option is to use the drawBitmap that does the scaling for you with the following call canvas.drawBitmap (Bitmap bitmap, Rect src, Rect dst, Paint paint)