关于Android Paint绘制颜色

Question

DrawView.java

public class DrawView extends View implements OnTouchListener {
private Canvas mCanvas;
private Path mPath;
public Paint mPaint;
ArrayList<Path> paths = new ArrayList<Path>();
private ArrayList<Path> undonePaths = new ArrayList<Path>();

private MaskFilter mEmboss;
private MaskFilter mBlur;

private Bitmap im;

public DrawView(Context context) {
    super(context);
    setFocusable(true);
    setFocusableInTouchMode(true);
    this.setOnTouchListener(this);

    paths.clear();
    undonePaths.clear();

    mPaint = new Paint();
    mPaint.setAntiAlias(true);
    mPaint.setDither(true);
    mPaint.setColor(Color.BLUE);
    mPaint.setStyle(Paint.Style.STROKE);
    mPaint.setStrokeJoin(Paint.Join.ROUND);
    mPaint.setStrokeCap(Paint.Cap.ROUND);
    mPaint.setStrokeWidth(4);
    mEmboss = new EmbossMaskFilter(new float[] { 1, 1, 1 }, 0.4f, 6, 3.5f);

    mBlur = new BlurMaskFilter(8, BlurMaskFilter.Blur.NORMAL);

    mCanvas = new Canvas();
    mPath = new Path();
    // paths.add(mPath);

    im = BitmapFactory.decodeResource(context.getResources(),
            R.drawable.ic_launcher);

}

@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    super.onSizeChanged(w, h, oldw, oldh);
}

@Override
protected void onDraw(Canvas canvas) {
    canvas.drawColor(Share.cColor);

    for (Path p : paths) {

        canvas.drawPath(p, mPaint);
    }

    canvas.drawPath(mPath, mPaint);

}

private float mX, mY;
private static final float TOUCH_TOLERANCE = 4;

private void touch_start(float x, float y) {

    mPaint.setColor(Share.dColor);
    undonePaths.clear();
    mPath.reset();
    mPath.moveTo(x, y);
    mX = x;
    mY = y;

    Log.e("", "pathsize:::" + paths.size());
    Log.e("", "undonepathsize:::" + undonePaths.size());
}

private void touch_move(float x, float y) {
    float dx = Math.abs(x - mX);
    float dy = Math.abs(y - mY);
    if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
        mPath.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);
        mX = x;
        mY = y;
    }
}

private void touch_up() {
    mPath.lineTo(mX, mY);
    // commit the path to our offscreen
    mCanvas.drawPath(mPath, mPaint);
    // kill this so we don't double draw
    paths.add(mPath);
    mPath = new Path();

    Log.e("", "pathsize:::" + paths.size());
    Log.e("", "undonepathsize:::" + undonePaths.size());
}

public void onClickUndo() {

    Log.e("", "pathsize:::" + paths.size());
    Log.e("", "undonepathsize:::" + undonePaths.size());
    if (paths.size() > 0) {
        undonePaths.add(paths.remove(paths.size() - 1));
        invalidate();
    } else {

    }
    // toast the user
}

public void onClickRedo() {

    Log.e("", "pathsize:::" + paths.size());
    Log.e("", "undonepathsize:::" + undonePaths.size());
    if (undonePaths.size() > 0) {
        paths.add(undonePaths.remove(undonePaths.size() - 1));
        invalidate();
    } else {

    }
    // toast the user
}

@Override
public boolean onTouch(View arg0, MotionEvent event) {
    float x = event.getX();
    float y = event.getY();

    switch (event.getAction()) {
    case MotionEvent.ACTION_DOWN:
        touch_start(x, y);
        invalidate();
        break;
    case MotionEvent.ACTION_MOVE:
        touch_move(x, y);
        invalidate();
        break;
    case MotionEvent.ACTION_UP:
        touch_up();
        invalidate();
        break;
    }
    return true;
}

}

我正在尝试用不同的颜色绘制手指画，但是每当我改变颜料的颜色时，所有以前的路径或绘图都会获取并使用更新的颜色进行绘制，我想用不同的颜色进行绘制，我该怎么做？请给我一些解决方案。

Answer 1

为此，您必须为每个绘制的对象创建一个新的Paint。这是因为当Canvas 重绘时，它每次都引用同一个Paint 对象，所以所有路径都会使用这个绘制。

首先，我将更改您的paths 数组以同时包含Paint 和Path。您可以使用 Android 类型 Pair 来实现此目的。

ArrayList<Pair<Path, Paint>> paths = new ArrayList<Pair<Path, Paint>>();

您还必须以这种方式转换您的 undonePaths 变量。

然后，在您的touch_up() 方法中，您需要添加这个新的Paint 对象。

Paint newPaint = new Paint(mPaint); // Clones the mPaint object
paths.add(new Pair<Path, Paint>(mPath, newPaint));

最后，您的循环也必须为此进行调整：

for (Pair<Path, Paint> p : paths) {
    canvas.drawPath(p.first, p.second);
}

这会占用大量内存，因此当这些项目不再使用时，您必须小心重置它们，但是要拥有这么多不同的颜色，您必须拥有所有这些不同的Paint 对象。