2023学年完整公开课版Canvas画布

《通信业务开发》课程Canvas画布Canvas画布2D绘图功能特性属性方法PART21-2实例演示View画框，装裱图画，展示在Activity中1234Canvas画布，提供绘图方法Paint画笔，可设置粗细、颜色、风格样式…Color颜料色彩根据ARGB调配色彩，供画笔使用5BitmapPathDrawableMatrix……图片、图形、路径、矩阵等其他工具…2D绘图功能特性示例画布提供绘图方法，绘制各种图形（如矩形、图形、线条等View中内嵌Canvas，绘图步骤定义绘图View：继承View为View实现带Context参数的构造函数覆写View.onDraw()在onDraw中，用Canvas、Paint、Color等绘制图形在Activity中加载显示自定义的View特性No.属性描述1drawCircledrawArcdrawOval绘制圆、圆弧、椭圆2

drawLine(s)绘制直线、连续折线3drawRectdrawRoundRect绘制矩形、圆角矩形4

drawTextdrawPostTextdrawTextOnPath绘制文字、偏移文字、沿路径文字5drawVertices绘制三角形面片6

drawPicture

在指定矩形中绘制Picture对象

7

drawBitmapdrawBitmapMesh绘制位图、使用mesh（网）绘制位图

8drawARGBdrawRGBdrawColor用指定颜色填充画布属性方法实例演示publicclassUnlockAcextendsActivity{@OverrideprotectedvoidonCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);setContentView(newUnlockView(this));}publicclassUnlockViewextendsView{intxCenter=0;intyCenter=0;intiRadiusB=25;intiRadiusW=8;publicUnlockView(Contextcontext){super(context);setBackgroundColor(Color.LTGRAY);}@OverrideprotectedvoidonDraw(Canvascanvas){xCenter=canvas.getWidth()/2;yCenter=canvas.getHeight()/2;PaintpWhite=newPaint(Paint.ANTI_ALIAS_FLAG);pWhite.setColor(Color.WHITE);pWhite.setStrokeWidth(2.0f);pWhite.setStyle(Paint.Style.FILL_AND_STROKE);PaintpBlack=newPaint(Paint.ANTI_ALIAS_FLAG);pBlack.setColor(Color.BLACK);

pBlack.setStrokeWidth(2.0f);pBlack.setStyle(Paint.Style.FILL);pBlack.setTextSize(15f);for(inti=-1;i<=1;i++){for(intj=-1;j<=1;j++){canvas.drawCircle(xCenter+80*i,yCenter+80*j,iRadiusB,pGray);canvas.drawCircle(xCenter+80*i,yCenter+80*j,iRadiusB,pBlack);canvas.drawCircle(xCenter+80*i,yCenter+80*j,iRadiusW,pWhite);}}canvas.drawText(