android 如何用画布绘制位图的局部

6psbrbz9 于 2022-12-09 发布在 Android

关注(0)|答案(2)|浏览(140)

我有一个

：
1.框架布局（标记为红色）
1.源图像视图（黑色）
1.具有OnTouchListener（橙子）的对象（图像视图）
通过带有OnTouchListener的Object，我想显示在imageview（源imageview）上填充的位图的一部分。
所以这不是一个问题，我这样做：
Bitmap bt = Bitmap.createBitmap(sourceBitmap,event.getX(),event.getY(),250,250);

所在地：

1.SourceBitmap-是添加到源ImageView的图像
1.event.getX（）/**event.getY（）**是一个坐标，我从这里开始绘制位图的一部分
1.250，250-其大小为部分位图（part）。
结果为：

因此，当我的对象（使用touchlistener）进入边界时，问题就出现了（我已经为橙子对象设置了这种可能性，使用Object.width（）/2将其移出边界）。
因此在本例中：

我怎样才能达到这个结果：

其中部分结果将是：
1.部分位图
1.第二部分是框架布局背景颜色。
我目前尝试的是：

public boolean onTouch(View view, MotionEvent event) {

    switch (event.getAction()) {
        case MotionEvent.ACTION_MOVE:

            //i want to draw bigger portion then corrds
            int CurrentX = (int)view.getX() - (view.getWidth());
            int CurrentY = (int)view.getY() - (view.getHeight());

            //case,when object is going out of border
            if(CurrentX <= 0)
            {
                Paint paint = new Paint();
                paint.setStyle( Style.FILL  );
                paint.setColor( Color.RED );

                mBitmap = Bitmap.CreateBitmap(sourceBitmap,(int)view.getX() + Math.abs(CurrentX),(int)view.getY(),250,250);
                Canvas canvas = new Canvas(mBitmap);
                canvas.drawBitmap(mBitmap,new Rect((int)view.getX()+Math.abs(CurrentX), (int)view.getY(),250-Math.abs(CurrentX),250),new RectF(Math.abs(CurrentX), 0, 250,250),paint);
            }
            break;
    }

    return true;
}
}

有什么建议吗？谢谢！

android

来源：https://stackoverflow.com/questions/34052186/how-to-draw-portion-of-bitmap-via-canvas-drawbitmap

2条答案

按热度按时间

dy1byipe1#

Solved by myself!
It was complicated,but result is pretty nice.
Here we go:
So for my case(when object with OnTouchListener can go out of border On X and Y axes),i've made Post Conditions(some kind of regulations).

Conditions

Width = Width of imageView,where i want to show result.
Height = Height of imageView,where i want to show result;

LeftSide

X_Coord < 0 && Y_Coord - Height / 2 < 0 && Y_Coord < Bitmap.Height
This is our Top Area.
X_Coord < 0 && Y_Coord - Height / 2 > 0 && Y_Coord < Bitmap.Height
This is our Middle Area.
X_Coord < 0 && Y_Coord - Height / 2 > 0 && Y_Coord > Bitmap.Height
This is our Bottom Area.

RightSide

X_Coord > Bitmap.Height && Y_Coord - Height / 2 > 0 && Y_Coord < Bitmap.Height
This is our Middle Area.
X_Coord > Bitmap.Height && Y_Coord - Height / 2 < 0 && Y_Coord < Bitmap.Height
This is our Top Area.
X_Coord > Bitmap.Height && Y_Coord - Height / 2 > 0 && Y_Coord > Bitmap.Height
This is our Bottom Area.

Standart(Area of Middle,that are not going to Left or Right side)

X_Coord - Width / 2 > 0 && X_Coord < Bitmap.Width && Y_Coord - Height / 2 < 0 && Y_Coord < Bitmap.Height
This is our Top Area.
X_Coord - Width / 2 > 0 && X_Coord < Bitmap.Width && Y_Coord - Height / 2 > 0 && Y_Coord > Bitmap.Height
This is our Bottom Area.
X_Coord - Width / 2 > 0 && X_Coord < Bitmap.Width && Y_Coord - Height / 2 > 0 && Y_Coord < Bitmap.Height
This is our Middle Area.
So via this "Conditions",i'm drawing portion of bitmap on my MotionEvent.ACTION_MOVE case.
Let's see some example:

public boolean onTouch(View view, MotionEvent event) {

    switch (event.getAction()) {
        case MotionEvent.ACTION_MOVE:

        int Width = ResultImgView.getWidth();
        int Height = ResultImgView.getHeight();
        //paint for our Red background
        Paint paint = new Paint();
        paint.setStyle( Style.FILL  );
        paint.setColor( Color.RED );
        Bitmap mBitmap = null;
        Canvas canvas = null;

        //Our Condition 
        if(view.getX() - Width / 2 >= SourceBitmap.getWidth() 
            && view.getY() - Height / 2 > 0 && view.getY() + Height / 2 <  SourceBitmap.getHeight())
        {
            //Nice,we entered here. Seems that we're now located at RightSide at Middle position
            //So let's draw part of bitmap.
            //our margin for X coords
            int Difference = (int)((view.getX() - Width / 2 ) - SourceBitmap.getWidth();
            //dont forget to put margin
            //BTW we're now took portion of bitmap
            mBitmap = Bitmap.createBitmap(SourceBitmap, ((int)view.getX() - Width / 2) - Difference, (int)view.getY() - Height / 2, Width,Height);
            canvas = new Canvas(mBitmap);
            //draw rect
            canvas.drawRect(0,0,mBitmap.getWidth(),mBitmap.getHeight(),paint);
            //draw portion of bitmap
            canvas.drawBitmap(mBitmap,new Rect(Difference, 0,mBitmap.getWidth(),mBitmap.getHeight()),new Rect(0,0,mBitmap.getWidth() - Difference,mBitmap.getHeight()),null);
            //and that's all!
        }

        //do the same for other  condition....etc
        break;
}


   return true;
}

Enjoy!

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wpx232ag2#

如果sourceBitmap只是ImageView中的位图集，那么结果是可以预测的。要实现您的目标，您需要：

FrameLayout坐标中的橙子正方形坐标。看起来你已经有了正确的坐标。
1.作为sourceBitmap，你必须使用FrameLayout.draw方法创建的Bitmap。注意你的橙子正方形必须不是FrameLayout's子对象。
如果你把你所有的代码贴在某个地方，我可以检查它。

赞(0）回复(0）举报 2022-12-09

我来回答

android 如何用画布绘制位图的局部

2条答案

Conditions

LeftSide

RightSide

Standart(Area of Middle,that are not going to Left or Right side)

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