Crop-to-fit image in Android

问题

I've been trying this for some time, I would like to create a wallpaper from a Bitmap. Let's say the desired wallpaper size is 320x480, and the source image size is 2048x2048.

I'm not sure whether crop-to-fit is the right term, but what I would like to achieve is to get most part of the picture that has the equal ratio as the desired wallpaper size (320x480).

So in this case, I would like to get 2048x1365 or (1365.333... to be exact) from the source Bitmap, and scale it down to 320x480.

The technique that I have tried is:

1) Crop the Bitmap into 2048x1365 first

bm = Bitmap.createBitmap(bm, xOffset, yOffset, 2048, 1365);

2) Scale it down to 320x480

bm = Bitmap.createScaledBitmap(bm, 320, 480, false);

which produced OutOfMemory error.

Is there any way to achieve this?

Regards,

dezull

回答1:

Thanks to open source, I found the answer from Android Gallery source code here at line 230 :-D

croppedImage = Bitmap.createBitmap(mOutputX, mOutputY, Bitmap.Config.RGB_565);
Canvas canvas = new Canvas(croppedImage);

Rect srcRect = mCrop.getCropRect();
Rect dstRect = new Rect(0, 0, mOutputX, mOutputY);

int dx = (srcRect.width() - dstRect.width()) / 2;
int dy = (srcRect.height() - dstRect.height()) / 2;

// If the srcRect is too big, use the center part of it.
srcRect.inset(Math.max(0, dx), Math.max(0, dy));

// If the dstRect is too big, use the center part of it.
dstRect.inset(Math.max(0, -dx), Math.max(0, -dy));

// Draw the cropped bitmap in the center
canvas.drawBitmap(mBitmap, srcRect, dstRect, null);

回答2:

I know this is an incredibly late reply, but something like this maybe:

public static Bitmap scaleCropToFit(Bitmap original, int targetWidth, int targetHeight){
    //Need to scale the image, keeping the aspect ration first
    int width = original.getWidth();
    int height = original.getHeight();

    float widthScale = (float) targetWidth / (float) width;
    float heightScale = (float) targetHeight / (float) height;
    float scaledWidth;
    float scaledHeight;

    int startY = 0;
    int startX = 0;

    if (widthScale > heightScale) {
        scaledWidth = targetWidth;
        scaledHeight = height * widthScale;
        //crop height by...
        startY = (int) ((scaledHeight - targetHeight) / 2);
    } else {
        scaledHeight = targetHeight;
        scaledWidth = width * heightScale;
        //crop width by..
        startX = (int) ((scaledWidth - targetWidth) / 2);
    }

    Bitmap scaledBitmap = Bitmap.createScaledBitmap(original, (int) scaledWidth, (int) scaledHeight, true);

    Bitmap resizedBitmap = Bitmap.createBitmap(scaledBitmap, startX, startY, targetWidth, targetHeight);
    return resizedBitmap;
}

回答3:

here is an answer that gets you most of the way there: How to crop an image in android?

来源：https://stackoverflow.com/questions/5226922/crop-to-fit-image-in-android

标签

android

image-manipulation