如何制作可绘制的适合画布

Question

I want to draw a Drawable on a canvas with a fixed size.

The problem is that the drawable draws itself on the canvas with its instrinsic with and height, and does not take all the space available.

I want to make the drawable fill all the space in canvas, like in an ImageView.

So I have take a look in ImageView source code, and see that matrix is used, I tried below but the drawable is still drawn on the top left corner with its instrinsic size.

For info, my drawable is a PictureDrawable, created from a Picture coming from an SVG file.

        Bitmap bitmap = Bitmap.createBitmap(fSize, fSize, Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);

        Drawable drawable = svg.createPictureDrawable();

        float scale = Math.min((float) fSize / (float) drawable.getIntrinsicWidth(),
                (float) fSize / (float) drawable.getIntrinsicHeight());

        Matrix matrix = new Matrix();
        matrix.setScale(scale, scale);

        canvas.setMatrix(matrix);

        drawable.draw(canvas);

Thanks.

Answer 1

You could render the SVG to a Picture , and then render that directly to the Canvas , with something along the lines of:

public Bitmap renderToBitmap(SVG svg, int requiredWidth){   
    if(requiredWidth < 1) requiredWidth = (int)svg.getIntrinsicWidth();

    float scaleFactor = (float)requiredWidth / (float)svg.getIntrinsicWidth();
    int adjustedHeight = (int)(scaleFactor * svg.getIntrinsicHeight());

    Bitmap bitmap = Bitmap.createBitmap(requiredWidth, adjustedHeight, Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(bitmap);
    canvas.drawPicture(svg.getPicture(), new Rect(0, 0, requiredWidth, adjustedHeight));

    return bitmap;
}

The above method will preserve the aspect ratio using the width as the scaling factor. If a value less than one is passed into the method (what you labeled fSize), it will use the intrinsic width of the image when generating the Bitmap .

Edit: For anyone using AndroidSVG instead of svg-android (like what I'm assuming is being used above), just replace all former occurrences of getIntrinsicWidth(), getIntrinsicHeight(), and getPicture() with getDocumentWidth(), getDocumentHeight(), and renderToPicture() , respectively.