android学习之绘图总结

以下是程序的运行结果：

代码如下：

package com.example.njupt.zhb.canvastest;import android.R.integer;import android.app.Activity;    import android.os.Bundle;    import android.view.View;    import android.content.Context;    import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Canvas;    import android.graphics.Color;    import android.graphics.DashPathEffect;import android.graphics.Paint;    import android.graphics.PathEffect;import android.graphics.RectF;    import android.graphics.Path;    import android.graphics.Shader;    import android.graphics.LinearGradient;  //主程序中继承自Android.view.View的 MyView类，重写 MyView的onDraw（）方法，   //一开始就会运行绘制的工作，在onDraw（）中以Paint将几何图形绘制在Canvas上，   //以 paint.setColor() 改变图形颜色、以 paint.setStyle()的设置来控制画出的的   //图形是空心还是实心。程序的最后一段，就是直接在Canvas写上文字，随着Paint对   //象里的属性设置，也会有不同的外观模式。public class MyDrawActivity extends Activity {        /** Called when the activity is first created. */       @Override       public void onCreate(Bundle savedInstanceState) {            super.onCreate(savedInstanceState);            /*设置ContentView为自定义的MyVieW*/           MyView myView=new MyView(this);            setContentView(myView);             }                 /* 自定义继承View 的MyView*/       private class MyView extends View {             public MyView(Context context){                super(context) ;             }                      /*重写onDraw（）*/            @Override            protected void onDraw(Canvas canvas)             {                     super.onDraw(canvas);                  /*设置背景为白色*/                 canvas.drawColor(Color.WHITE);                                     Paint paint=new Paint();                  /*去锯齿*/                 paint.setAntiAlias(true);                  /*设置paint的颜色*/                 paint.setColor(Color.RED);                  /*设置paint的 style 为STROKE：空心*/                 paint.setStyle(Paint.Style.STROKE);                  /*设置paint的外框宽度*/                 paint.setStrokeWidth(3);                                     /*画一个空心圆形*/                 canvas.drawCircle(40, 40, 30, paint);                  /*画一个空心正方形*/                 canvas.drawRect(10, 90, 70, 150, paint);                  /*画一个空心长方形*/                 canvas.drawRect(10, 170, 70,200, paint);                  /*画一个空心椭圆形*/                 canvas.drawOval(new RectF(10,220,70,250), paint);                  /*画一个空心三角形*/                 Path path=new Path();                  path.moveTo(10, 330);                  path.lineTo(70,330);                  path.lineTo(40,270);                  path.close();                  canvas.drawPath(path, paint);                  /*画一个空心梯形*/                 Path path1=new Path();                  path1.moveTo(10, 410);                  path1.lineTo(70,410);                  path1.lineTo(55,350);                  path1.lineTo(25, 350);                  path1.close();                  canvas.drawPath(path1, paint);                                     /*设置paint的颜色*/                 paint.setColor(Color.BLUE);                  /*设置paint 的style为 FILL：实心*/                 paint.setStyle(Paint.Style.FILL);                  /*画一个实心圆*/                 canvas.drawCircle(120,40,30, paint);                  /*画一个实心正方形*/                 canvas.drawRect(90, 90, 150, 150, paint);                  /*画一个实心长方形*/                 canvas.drawRect(90, 170, 150,200, paint);                  /*画一个实心椭圆*/                 RectF re2=new RectF(90,220,150,250);                  canvas.drawOval(re2, paint);                  /*画一个实心三角形*/                 Path path2=new Path();                  path2.moveTo(90, 330);                  path2.lineTo(150,330);                  path2.lineTo(120,270);                  path2.close();                  canvas.drawPath(path2, paint);                  /*画一个实心梯形*/                 Path path3=new Path();                  path3.moveTo(90, 410);                  path3.lineTo(150,410);                  path3.lineTo(135,350);                  path3.lineTo(105, 350);                  path3.close();                  canvas.drawPath(path3, paint);                                     /*设置渐变色*/                 Shader mShader=new LinearGradient(0,0,100,100,                          new int[]{Color.RED,Color.GREEN,Color.BLUE,Color.YELLOW},                          null,Shader.TileMode.REPEAT);                  //Shader.TileMode三种模式                  //REPEAT:沿着渐变方向循环重复                  //CLAMP:如果在预先定义的范围外画的话，就重复边界的颜色                  //MIRROR:与REPEAT一样都是循环重复，但这个会对称重复                  paint.setShader(mShader);//用Shader中定义定义的颜色来话                                  /*画一个渐变色圆*/                 canvas.drawCircle(200,40,30, paint);                  /*画一个渐变色正方形*/                 canvas.drawRect(170, 90, 230, 150, paint);                  /*画一个渐变色长方形*/                 canvas.drawRect(170, 170, 230,200, paint);                  /*画一个渐变色椭圆*/                 RectF re3=new RectF(170,220,230,250);                  canvas.drawOval(re3, paint);                  /*画一个渐变色三角形*/                 Path path4=new Path();                  path4.moveTo(170,330);                  path4.lineTo(230,330);                  path4.lineTo(200,270);                  path4.close();                  canvas.drawPath(path4, paint);                  /*画一个渐变色梯形*/                 Path path5=new Path();                  path5.moveTo(170, 410);                  path5.lineTo(230,410);                  path5.lineTo(215,350);                  path5.lineTo(185, 350);                  path5.close();                  canvas.drawPath(path5, paint);                  /*写字*/                 paint.setTextSize(24);                  canvas.drawText("圆形", 240, 50, paint);                  canvas.drawText("正方形", 240, 120, paint);                  canvas.drawText("长方形", 240, 190, paint);                  canvas.drawText("椭圆形", 240, 250, paint);                  canvas.drawText("三角形", 240, 320, paint);                  canvas.drawText("梯形", 240, 390, paint);               /*虚线和虚线圆*/              paint.setStyle(Paint.Style.STROKE);                paint.setColor(Color.BLUE);              DashPathEffect effects = new DashPathEffect(new float[]{5,5,5,5},1);                paint.setPathEffect(effects);              canvas.drawCircle(120, 460, 50, paint);              canvas.drawLine(0, 400, 240, 400, paint);              /*画位图*/              Bitmap bitmap=BitmapFactory.decodeResource(getResources(), R.drawable.lenna);              RectF dst=new RectF(10,500,bitmap.getWidth()/2+10,bitmap.getHeight()/2+500);              canvas.drawBitmap(bitmap, null, dst, paint);         }               }    }