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I have followed the tutorial and succesfully created a Rotatory knob but it rotate full 360 degree. without stoping . I want to rotate it from 150 to 210 degrees as shown by the progress. .. How could i modify it to rotate between 150 and 210 degrees. My effort I have added given check in onDraw function protected void onDraw(Canvas c) { if(!(angle >150 && angle <210)) c.rotate(angle,getWidth()/2,getHeight()/2); super.onDraw(c); } But first time it stop it and take it back to 180 degree but as i rotate twice or thrice. The angle may be increment to 430 degree or above and my check don't work.

I'm trying to draw custom UI (a path in this case) on top of a Gallery. I've extended the base Gallery class and overwritten the draw method like this: public class MyGallery extends Gallery { ... @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); canvas.drawPath(mPath, mPaint); } I thought that putting my path drawing after super.onDraw would make sure that the path was drawn on top of the gallery AND it's child views, but instead the child views are layered on top of my path. Does anyone know how to draw this properly? (I know I could include a RelativeLayout and layer a

Here's my OnDraw() method void onDraw(Canvas canvas) { mCanvas = canvas; //invalidate(); int x = 0; Iterator<Letter> it = mNextUpQueue.iterator(); while(it.hasNext()){ mCanvas.drawBitmap(it.next().getNext(), mNextUpCoordinates.get(x).x, mNextUpCoordinates.get(x).y, mPaint); mCanvas.drawBitmap(mAvailableLetters.get(x).getNotPressed(), mAvailableLettersCoordinates.get(x).x, mAvailableLettersCoordinates.get(x).y, mPaint); x++; } } I have set canvas to a global variable mCanvas. But if I try to paint on mCanvas from outside the onDraw() method I get an error. Is it because I'm doing something

I have some methods in my View that modify some of the shapes that are drawn when called. In Java in order to make sure the component is updated I would call repaint() . Is there something that will make sure my view is updated correctly? I had read somewhere that calling invalidate() in the onDraw() method would keep things up to date and therefore I wouldn't need to have something like repaint() in my methods that modify that shapes that are drawn. Is this correct, or is there something else I have to do? EDIT To add in an example, a method I call in my view is: public void setLineThickness

转载请注明出处： http://blog.csdn.net/singwhatiwanna/article/details/38426471 （来自singwhatiwanna的csdn博客） Android View系统解析系列： Android View系统解析(上) 介绍View的基础知识、View的滑动、弹性滑动、滑动冲突解决方式、事件分发等 Android View系统解析(下) 介绍View的Framework层原理、View的measure / layout / draw三大流程和一些高级技巧 本次主要介绍下半部分，提纲如下 View的绘制过程 measure/layout/draw 工作流程 识别 MeasureSpec 并能够 make 合适的 MeasureSpec 在渲染前获取 View 的宽高 构造特殊的 View 自定义View 自定义View分类 自定义 View 须知 一 View的绘制过程 初识 ViewRoot ViewRoot 对应于 ViewRootImpl 类，是连接 WindowManager 和 DecorView 的纽带。 ActivityThread 中当 activity 对象被创建好后，会将 DecorView 加入到 Window中同时完成 ViewRootImpl 的创建并建立和 DecorView 的联系。 root =