Android：圆形可绘制对象

Question

我制作了这个 Custom Drawable，它应该将任何 Drawable 夹在圆圈中。但是在我的实现中，传递的drawable是原始形式的输出，而不是循环形式。

public class CircularDrawable extends Drawable {
    Paint mPaint,xfermodePaint;
    Drawable mDrawable;
    int[] vinylCenter = new int[2];
    int radius;
    Bitmap src;
    PorterDuffXfermode xfermode;
    Rect rect;
    Canvas testCanvas;
    public CircularDrawable(Drawable drawable) {
        mDrawable = drawable;
        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mPaint.setColor(0xffffffff);
        mPaint.setStyle(Paint.Style.FILL);
        xfermodePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        xfermode=new PorterDuffXfermode(PorterDuff.Mode.SRC_IN);
        xfermodePaint.setXfermode(xfermode);
        testCanvas=new Canvas();
    }

    @Override
    public void setBounds(Rect bounds) {
        super.setBounds(bounds);
        mDrawable.setBounds(bounds);
    }

    @Override
    public void setBounds(int left, int top, int right, int bottom) {
        super.setBounds(left, top, right, bottom);
        mDrawable.setBounds(left, top, right, bottom);
    }

    @Override
    protected void onBoundsChange(Rect bounds) {
        super.onBoundsChange(bounds);
        vinylCenter[0] = bounds.width() / 2;
        vinylCenter[1] = bounds.height() / 2;
        radius = (bounds.right - bounds.left) / 2;
        src = Bitmap.createBitmap(bounds.width(), bounds.height(), Bitmap.Config.ARGB_8888);
        testCanvas.setBitmap(src);
    }


    @Override
    public void draw(Canvas canvas) {
        canvas.save();
        canvas.drawARGB(0, 0, 0, 0);
        canvas.drawCircle(vinylCenter[0],vinylCenter[1],radius,mPaint);
        mDrawable.draw(testCanvas);
        canvas.drawBitmap(src,0f,0f,xfermodePaint);
    }



    @Override
    public void setAlpha(int alpha) {/*ignored*/}

    @Override
    public void setColorFilter(ColorFilter colorFilter) {/*ignored*/}

    @Override
    public int getOpacity() {
        /*ignored*/
        return 0;
    }
}

我的错误是什么？

我还使用 SquareImageview 来显示这个 drawable，它只是在 onMeasure 中使视图成为正方形。此问题不适用于 Circular imageview。

Answer 1

canvas 在使用 Porter/Duff xfermode 模式时默认情况下没有打开 alpha 通道（根据我在 android 中的经验）。这就是输出整个图像（src）的原因。 Porter/Duff xfermode 行为基于 Alpha 通道。

在 Circular Drawable 2 Canvas 的许多实现中，其中一个给出了 RGB 图像位图，另一个仅给出了带有圆形掩码的 alpha 通道位图。 Porter/Duff 应用了 xfer 模式，结果绘制在主 canvas。

我的错误是我没有指定绘制函数的 canvas alpha 通道将被考虑为 xfermode 使用 canvas 上的图层。

绘图函数将变为

@Override
public void draw(Canvas canvas) {
    int sc = canvas.saveLayer(null, null,
                    Canvas.HAS_ALPHA_LAYER_SAVE_FLAG |
                    );
    canvas.drawCircle(vinylCenter[0],vinylCenter[1],radius,mPaint);
    mDrawable.draw(testCanvas);
    canvas.drawBitmap(src,0f,0f,xfermodePaint);
    canvas.restoreToCount(sc);
}

保存图层以使用标志指示 alpha 通道，然后使用 xfermode。最后将其恢复到保存计数。

Answer 2

所以基本上我用这个方法来得到圆角图像

public static Bitmap getRoundedCornerBitmap(Bitmap bitmap, int pixels) {
    Bitmap output = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(output);

    final int color = 0xff424242;
    final Paint paint = new Paint();
    final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
    final RectF rectF = new RectF(rect);
    final float roundPx = pixels;

    paint.setAntiAlias(true);
    canvas.drawARGB(0, 0, 0, 0);
    paint.setColor(color);
    canvas.drawRoundRect(rectF, roundPx, roundPx, paint);

    paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
    canvas.drawBitmap(bitmap, rect, rect, paint);

    return output;

但是就像你指出的那样有时它不起作用，它确实起作用，但大多数时候发生的是你的 imageview 可能将其 scaletype 设置为 centerCrop 和其他类型，我所做的是我首先将我的图像高度压缩到与我的图像视图相同的高度和宽度，以便整个图像适合图像视图并且不会发生缩放，或者我只是计算使用此函数基于多少角高度进行舍入身高

   private int calculatePercentage(int percentage, int target)
{
    int k = (int)(target*(percentage/100.0f));
    return k;

}

所以我使用我的代码：图像高度的 new Bitmap(getRoundedCornerBitmap(bmp, calculatePercentage(5, bmp.getHeight()))); where 5 is 5 这为所有图像提供了相同的曲线，因为有些图像比其他图像大 `

Answer 3

For rounded imageview you can use this code 

    public class RoundedImageView extends ImageView {

    public RoundedImageView(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
    }

    public RoundedImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public RoundedImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    @Override
    protected void onDraw(Canvas canvas) {

        Drawable drawable = getDrawable();

        if (drawable == null) {
            return;
        }

        if (getWidth() == 0 || getHeight() == 0) {
            return;
        }
        Bitmap b = ((BitmapDrawable) drawable).getBitmap();
        Bitmap bitmap = b.copy(Bitmap.Config.ARGB_8888, true);

        int w = getWidth();//, h = getHeight();

        Bitmap roundBitmap = getCroppedBitmap(bitmap, w);
        canvas.drawBitmap(roundBitmap, 0, 0, null);

    }

    public static Bitmap getCroppedBitmap(Bitmap bmp, int radius)
    {
        Bitmap sbmp;
        if (bmp.getWidth() != radius || bmp.getHeight() != radius)
            sbmp = Bitmap.createScaledBitmap(bmp, radius, radius, false);
        else
            sbmp = bmp;
        Bitmap output = Bitmap.createBitmap(sbmp.getWidth(), sbmp.getHeight(),Config.ARGB_8888);
        Canvas canvas = new Canvas(output);

//      final int color = 0xffa19774;
        final Paint paint = new Paint();
        final Rect rect = new Rect(0, 0, sbmp.getWidth(), sbmp.getHeight());

        paint.setAntiAlias(true);
        paint.setFilterBitmap(true);
        paint.setDither(true);
        canvas.drawARGB(0, 0, 0, 0);
//      paint.setColor(Color.parseColor("#BAB399"));
        paint.setColor(Color.parseColor("#FF0000"));
        canvas.drawCircle(sbmp.getWidth() / 2 + 0.7f, sbmp.getHeight() / 2 + 0.7f, sbmp.getWidth() / 2 + 0.1f, paint);
        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
        canvas.drawBitmap(sbmp, rect, rect, paint);

        return output;
    }
}

Answer 4

您已经在支持库 v4 中优化了圆形可绘制对象的实现：

Google reference

 /**
* A Drawable that wraps a bitmap and can be drawn with rounded corners. You can create a
* RoundedBitmapDrawable from a file path, an input stream, or from a
* {@link android.graphics.Bitmap} object.
* <p>
* Also see the {@link android.graphics.Bitmap} class, which handles the management and
* transformation of raw bitmap graphics, and should be used when drawing to a
* {@link android.graphics.Canvas}.
* </p>
*/
public abstract class RoundedBitmapDrawable extends Drawable ....

Answer 5

For circular imageview use the below code

public class RoundedImageView extends ImageView {

    public RoundedImageView(Context context) {
        super(context);
    }

    public RoundedImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public RoundedImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        BitmapDrawable drawable = (BitmapDrawable) getDrawable();

        if (drawable == null) {
            return;
        }

        if (getWidth() == 0 || getHeight() == 0) {
            return;
        }

        Bitmap fullSizeBitmap = drawable.getBitmap();

        int scaledWidth = getMeasuredWidth();
        int scaledHeight = getMeasuredHeight();

        /*
         * scaledWidth = scaledWidth/2; scaledHeight = scaledHeight/2;
         */

        Bitmap mScaledBitmap;
        if (scaledWidth == fullSizeBitmap.getWidth()
                && scaledHeight == fullSizeBitmap.getHeight()) {
            mScaledBitmap = fullSizeBitmap;
        } else {
            mScaledBitmap = Bitmap.createScaledBitmap(fullSizeBitmap,
                    scaledWidth, scaledHeight, true /* filter */);
        }

        // Bitmap roundBitmap = getRoundedCornerBitmap(mScaledBitmap);

        // Bitmap roundBitmap = getRoundedCornerBitmap(getContext(),
        // mScaledBitmap, 10, scaledWidth, scaledHeight, false, false,
        // false, false);
        // canvas.drawBitmap(roundBitmap, 0, 0, null);

        Bitmap circleBitmap = getCircledBitmap(mScaledBitmap);

        canvas.drawBitmap(circleBitmap, 0, 0, null);

    }

    public Bitmap getRoundedCornerBitmap(Context context, Bitmap input,
            int pixels, int w, int h, boolean squareTL, boolean squareTR,
            boolean squareBL, boolean squareBR) {

        Bitmap output = Bitmap.createBitmap(w, h, Config.ARGB_8888);
        Canvas canvas = new Canvas(output);
        final float densityMultiplier = context.getResources()
                .getDisplayMetrics().density;

        final int color = 0xff424242;

        final Paint paint = new Paint();
        final Rect rect = new Rect(0, 0, w, h);
        final RectF rectF = new RectF(rect);

        // make sure that our rounded corner is scaled appropriately
        final float roundPx = pixels * densityMultiplier;

        paint.setAntiAlias(true);
        canvas.drawARGB(0, 0, 0, 0);
        paint.setColor(color);
        canvas.drawRoundRect(rectF, roundPx, roundPx, paint);

        // draw rectangles over the corners we want to be square
        if (squareTL) {
            canvas.drawRect(0, 0, w / 2, h / 2, paint);
        }
        if (squareTR) {
            canvas.drawRect(w / 2, 0, w, h / 2, paint);
        }
        if (squareBL) {
            canvas.drawRect(0, h / 2, w / 2, h, paint);
        }
        if (squareBR) {
            canvas.drawRect(w / 2, h / 2, w, h, paint);
        }

        paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
        canvas.drawBitmap(input, 0, 0, paint);

        return output;
    }

    Bitmap getCircledBitmap(Bitmap bitmap) {

        Bitmap result = Bitmap.createBitmap(bitmap.getWidth(),
                bitmap.getHeight(), Bitmap.Config.ARGB_8888);

        Canvas canvas = new Canvas(result);

        int color = Color.BLUE;
        Paint paint = new Paint();
        Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());

        paint.setAntiAlias(true);
        canvas.drawARGB(0, 0, 0, 0);
        paint.setColor(color);
        // canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
        canvas.drawCircle(bitmap.getWidth() / 2, bitmap.getHeight() / 2,
                bitmap.getHeight() / 2, paint);

        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
        canvas.drawBitmap(bitmap, rect, rect, paint);

        return result;
    }

}

Answer 6

如果您正在使用 PorterDuffXfermode:

，请尝试禁用硬件加速

整个 activity 的清单中：

<activity android:hardwareAccelerated="false" />

或者在您使用 xfermode 的特定视图上：

myView.setLayerType(View.LAYER_TYPE_SOFTWARE, null);

Android：圆形可绘制对象

Android: Circular Drawable

android

drawable

porter-duff