canvas.drawPosText:
@Override
protected void onDraw(Canvas canvas) {
//按照既定点 绘制文本内容
canvas.drawPosText("Android777", new float[]{
10,10, //第一个字母在坐标10,10
20,20, //第二个字母在坐标20,20
30,30, //....
40,40,
50,50,
60,60,
70,70,
80,80,
90,90,
100,100
}, paint);
}
canvas.drawRect:
@Override
protected void onDraw(Canvas canvas) {
RectF rect = new RectF(50, 50, 200, 200);
canvas.drawRect(rect, paint);
}
}
canvas.drawRoundRect:
@Override
protected void onDraw(Canvas canvas) {
RectF rect = new RectF(50, 50, 200, 200);
canvas.drawRoundRect(rect,
30, //x轴的半径
30, //y轴的半径
paint);
}
canvas.drawPath:
@Override
protected void onDraw(Canvas canvas) {
Path path = new Path(); //定义一条路径
path.moveTo(10, 10); //移动到 坐标10,10
path.lineTo(50, 60);
path.lineTo(200,80);
path.lineTo(10, 10);
canvas.drawPath(path, paint);
}
canvas.drawTextOnPath:
@Override
protected void onDraw(Canvas canvas) {
Path path = new Path(); //定义一条路径
path.moveTo(10, 10); //移动到 坐标10,10
path.lineTo(50, 60);
path.lineTo(200,80);
path.lineTo(10, 10);
//
canvas.drawPath(path, paint);
canvas.drawTextOnPath("Android777开发者博客", path, 10, 10, paint);
}
位置转换方法,canvas.rorate和canvas.translate:
@Override
protected void onDraw(Canvas canvas) {
paint.setAntiAlias(true);
paint.setStyle(Style.STROKE);
canvas.translate(canvas.getWidth()/2, 200); //将位置移动画纸的坐标点:150,150
canvas.drawCircle(0, 0, 100, paint); //画圆圈
//使用path绘制路径文字
canvas.save();
canvas.translate(-75, -75);
Path path = new Path();
path.addArc(new RectF(0,0,150,150), -180, 180);
Paint citePaint = new Paint(paint);
citePaint.setTextSize(14);
citePaint.setStrokeWidth(1);
canvas.drawTextOnPath("http://www.android777.com", path, 28, 0, citePaint);
canvas.restore();
Paint tmpPaint = new Paint(paint); //小刻度画笔对象
tmpPaint.setStrokeWidth(1);
float y=100;
int count = 60; //总刻度数
for(int i=0 ; i <count ; i++){
if(i%5 == 0){
canvas.drawLine(0f, y, 0, y+12f, paint);
canvas.drawText(String.valueOf(i/5+1), -4f, y+25f, tmpPaint);
}else{
canvas.drawLine(0f, y, 0f, y +5f, tmpPaint);
}
canvas.rotate(360/count,0f,0f); //旋转画纸
}
//绘制指针
tmpPaint.setColor(Color.GRAY);
tmpPaint.setStrokeWidth(4);
canvas.drawCircle(0, 0, 7, tmpPaint);
tmpPaint.setStyle(Style.FILL);
tmpPaint.setColor(Color.YELLOW);
canvas.drawCircle(0, 0, 5, tmpPaint);
canvas.drawLine(0, 10, 0, -65, paint);
}
上面几个例子基本已经将常用的canvas.draw*方法测试过了,我们结合一些事件,做一些有用户交互的应用:
package com.android777.demo.uicontroller.graphics;
import java.util.ArrayList;
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PointF;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
public class CanvasDemoActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new CustomView1(this));
}
/**
* 使用内部类 自定义一个简单的View
* @author Administrator
*
*/
class CustomView1 extends View{
Paint paint;
private ArrayList<PointF> graphics = new ArrayList<PointF>();
PointF point;
public CustomView1(Context context) {
super(context);
paint = new Paint(); //设置一个笔刷大小是3的黄色的画笔
paint.setColor(Color.YELLOW);
paint.setStrokeJoin(Paint.Join.ROUND);
paint.setStrokeCap(Paint.Cap.ROUND);
paint.setStrokeWidth(3);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
graphics.add(new PointF(event.getX(),event.getY()));
invalidate(); //重新绘制区域
return true;
}
//在这里我们将测试canvas提供的绘制图形方法
@Override
protected void onDraw(Canvas canvas) {
for (PointF point : graphics) {
canvas.drawPoint(point.x, point.y, paint);
}
//
super.onDraw(canvas);
}
}
}
当用户点击时将出现一个小点,拖动时将画出一条用细点组成的虚线:
canvas的应用
canva还可以制作很多自定义控件,比如google日历的monthview就是用canvas绘制出来的,github上有很多使用canva的项目,所有的图表库都是用canvas绘制的。