我如何画一个局部的位图弧？像一个圆轮进步，但与位图，它变得越来越显示。 [英] How do I draw a partial bitmap-arc? Like a circular progress wheel, but with a bitmap that gets more and more displayed.

问题描述

我正在寻找，是揭示顺时针循环方式的图像的示意图。当进度为25％应在第一90度被揭示且当其100％的全360度应绘制

What I am searching for, is a view that reveals an image in a clockwise circular fashion. When the progress is 25% the first 90 degrees should be revealed and when its 100% the full 360 degrees should be drawn.

有非常接近使用canvas.drawArc（），但这种方法只适用于油漆对象，而不是位图。

It is very close to using the canvas.drawArc(), but this method only works with Paint objects, not bitmaps.

其他答案也只有以饱满的颜色的工作： <一href="http://stackoverflow.com/questions/14688117/how-to-make-circle-custom-progress-bar-in-android">How为了使圆自定义进度条的Andr​​oid

Other answers also only work with full colors: How To Make Circle Custom Progress Bar in Android

我发现这是一个非常困难的问题，我希望有人有一个解决方案。

I have found it to be a very hard problem, I hope someone has a solution.

推荐答案

TRE这样的：

public class MyView extends View {

    private Bitmap mBitmap;
    private Paint mPaint;
    private RectF mOval;
    private float mAngle = 135;
    private Paint mTextPaint;

    public MyView(Context context) {
        super(context);
        // use your bitmap insted of R.drawable.ic_launcher
        mBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mOval = new RectF();
        mTextPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mTextPaint.setTextSize(48);
        mTextPaint.setTextAlign(Align.CENTER);
        mTextPaint.setColor(0xffffaa00);
        mTextPaint.setTypeface(Typeface.DEFAULT_BOLD);
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        Matrix m = new Matrix();
        RectF src = new RectF(0, 0, mBitmap.getWidth(), mBitmap.getHeight());
        RectF dst = new RectF(0, 0, w, h);
        m.setRectToRect(src, dst, ScaleToFit.CENTER);
        Shader shader = new BitmapShader(mBitmap, TileMode.CLAMP, TileMode.CLAMP);
        shader.setLocalMatrix(m);
        mPaint.setShader(shader);
        m.mapRect(mOval, src);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        canvas.drawColor(0xff0000aa);
        canvas.drawArc(mOval, -90, mAngle, true, mPaint);
        canvas.drawText("click me", getWidth() / 2, getHeight() / 2, mTextPaint);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        float w2 = getWidth() / 2f;
        float h2 = getHeight() / 2f;
        mAngle = (float) Math.toDegrees(Math.atan2(event.getY() - h2, event.getX() - w2));
        mAngle += 90 + 360;
        mAngle %= 360;
        invalidate();
        return true;
    }
}

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