Question

我需要创建一个自定义的Drawable对象。我希望这个自定义drawable显示一个渐变，例如，它将作为视图的背景应用。为此，我重写了Drawable类的draw方法。我的CustomDrawable类的代码如下所示：

public void draw(Canvas canvas) {
    Rect clipBounds = canvas.getClipBounds();
    Paint rectanglePaint = new Paint();

    LinearGradient lg = new LinearGradient(0,0,0,clipBounds.height(),0xff838383,0xff242424,Shader.TileMode.CLAMP);
    rectanglePaint.setShader(lg);

    RectF rectangle = new RectF(0f,0.0f, clipBounds.width(), clipBounds.height()); //in pixels
    canvas.drawRoundRect(rectangle, 0f, 0f, rectanglePaint);
}

当我在onCreate方法中将此drawable指定为我的窗口的背景时，会出现问题。渐变看起来没有任何问题，但看起来它是缩放的，看起来真的很糟糕。

奇怪的是，我只用XML创建了一个等效的drawable，我在布局XML中将它直接指定为背景我没有这种uggly缩放效果（我只是添加以下行“window.setFormat（PixelFormat。 RGBA_8888）;“）

为什么我以编程方式执行此操作时没有相同的结果？

每个想法都会真的变得渺茫！感谢您阅读;）

Answer 1

我在我的项目中多次偶然发现同样的问题，每次由于时间不够（和懒惰），我会对一个不太理想的解决方案感到满意。但最近我找到了一些时间来打击这个特殊问题。这是我的解决方案，我希望它对你也有所帮助。

Bitmap scaleDownLargeImageWithAspectRatio(Bitmap image)
            {
                int imaheVerticalAspectRatio,imageHorizontalAspectRatio;
                float bestFitScalingFactor=0;
                float percesionValue=(float) 0.2;

                //getAspect Ratio of Image
                int imageHeight=(int) (Math.ceil((double) image.getHeight()/100)*100);
                int imageWidth=(int) (Math.ceil((double) image.getWidth()/100)*100);
                int GCD=BigInteger.valueOf(imageHeight).gcd(BigInteger.valueOf(imageWidth)).intValue();
                imaheVerticalAspectRatio=imageHeight/GCD;
                imageHorizontalAspectRatio=imageWidth/GCD;
                Log.i("scaleDownLargeImageWIthAspectRatio","Image Dimensions(W:H): "+imageWidth+":"+imageHeight);
                Log.i("scaleDownLargeImageWIthAspectRatio","Image AspectRatio(W:H): "+imageHorizontalAspectRatio+":"+imaheVerticalAspectRatio);

                //getContainer Dimensions
                int displayWidth = getWindowManager().getDefaultDisplay().getWidth();
                int displayHeight = getWindowManager().getDefaultDisplay().getHeight();
               //I wanted to show the image to fit the entire device, as a best case. So my ccontainer dimensions were displayWidth & displayHeight. For your case, you will need to fetch container dimensions at run time or you can pass static values to these two parameters 

                int leftMargin = 0;
                int rightMargin = 0;
                int topMargin = 0;
                int bottomMargin = 0;
                int containerWidth = displayWidth - (leftMargin + rightMargin);
                int containerHeight = displayHeight - (topMargin + bottomMargin);
                Log.i("scaleDownLargeImageWIthAspectRatio","Container dimensions(W:H): "+containerWidth+":"+containerHeight);

                //iterate to get bestFitScaleFactor per constraints
                while((imageHorizontalAspectRatio*bestFitScalingFactor <= containerWidth) && 
                        (imaheVerticalAspectRatio*bestFitScalingFactor<= containerHeight))
                {
                    bestFitScalingFactor+=percesionValue;
                }

                //return bestFit bitmap
                int bestFitHeight=(int) (imaheVerticalAspectRatio*bestFitScalingFactor);
                int bestFitWidth=(int) (imageHorizontalAspectRatio*bestFitScalingFactor);
                Log.i("scaleDownLargeImageWIthAspectRatio","bestFitScalingFactor: "+bestFitScalingFactor);
                Log.i("scaleDownLargeImageWIthAspectRatio","bestFitOutPutDimesions(W:H): "+bestFitWidth+":"+bestFitHeight);
                image=Bitmap.createScaledBitmap(image, bestFitWidth,bestFitHeight, true);

                //Position the bitmap centre of the container
                int leftPadding=(containerWidth-image.getWidth())/2;
                int topPadding=(containerHeight-image.getHeight())/2;
                Bitmap backDrop=Bitmap.createBitmap(containerWidth, containerHeight, Bitmap.Config.RGB_565);
                Canvas can = new Canvas(backDrop);
                can.drawBitmap(image, leftPadding, topPadding, null);

                return backDrop;
            }

以编程方式创建的Android Drawable对象是uggly（缩放）

1 个答案: