mupdf：android 库：如何反转颜色或更改为夜间模式

Question

如果有人使用mupdf android 库知道如何反转背景。我想给ui添加一个按钮

Answer 1

这很简单。在 PageView 中渲染位图时只需反转位图。

mEntire.setImageBitmap(invert(mEntireBm));
mPatch.setImageBitmap(invert(mPatchBm));

这是反转位图的方法。

    private Bitmap invert(Bitmap src) {
        int height = src.getHeight();
        int width = src.getWidth();

        Bitmap bitmap = Bitmap.createBitmap(width, height, src.getConfig());
        Canvas canvas = new Canvas(bitmap);
        Paint paint = new Paint();

        ColorMatrix matrixGrayscale = new ColorMatrix();
        matrixGrayscale.setSaturation(0);

        ColorMatrix matrixInvert = new ColorMatrix();
        matrixInvert.set(new float[]
                {
                        -1.0f, 0.0f, 0.0f, 0.0f, 255.0f,
                        0.0f, -1.0f, 0.0f, 0.0f, 255.0f,
                        0.0f, 0.0f, -1.0f, 0.0f, 255.0f,
                        0.0f, 0.0f, 0.0f, 1.0f, 0.0f
                });
        matrixInvert.preConcat(matrixGrayscale);

        ColorMatrixColorFilter filter = new ColorMatrixColorFilter(matrixInvert);
        paint.setColorFilter(filter);

        canvas.drawBitmap(src, 0, 0, paint);
        // src.recycle();
        return bitmap;
    }