18.图形和图像处理技术

画笔和画布的使用

绘制几何图形

package com.example.pratice9;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.RectF;
import android.view.View;

public class MyView extends View {
    public MyView(Context context) {
        super(context);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        //绘制机器人
        //创建一个画笔
        Paint paint = new Paint();
        //采用抗锯齿功能
        paint.setAntiAlias(true);
        paint.setColor(0xFFA4C739);//设置画笔颜色为绿色

        //绘制机器人的头
        RectF rectF = new RectF(10,10,100,100);//定义外轮廓矩形
        rectF.offset(90,20);
        canvas.drawArc(rectF,-10,-160,false,paint);

        //绘制眼睛
        paint.setColor(0xFFFFFFFF);//设置画笔颜色为白色
        canvas.drawCircle(165,53,4,paint);
        canvas.drawCircle(125,53,4,paint);

        //绘制天线
        paint.setStrokeWidth(2);//设置笔触宽度
        paint.setColor(0xFFA4C739);
        canvas.drawLine(110,15,125,35,paint);
        canvas.drawLine(180,15,165,35,paint);

        //绘制身体
        canvas.drawRect(100,75,190,150,paint);//绘制矩形
        RectF rectF_body = new RectF(100,140,190,160);
        canvas.drawRoundRect(rectF_body,10,10,paint);

        //绘制胳膊
        RectF rectF_arm = new RectF(75,75,95,140);
        canvas.drawRoundRect(rectF_arm,10,10,paint);
        rectF_arm.offset(120,0);//调整偏移位置
        canvas.drawRoundRect(rectF_arm,10,10,paint);

        //绘制腿
        RectF rectF_leg = new RectF(115,150,135,200);
        canvas.drawRoundRect(rectF_leg,10,10,paint);
        rectF_leg.offset(40,0);//调整偏移位置
        canvas.drawRoundRect(rectF_leg,10,10,paint);
    }}

注：

运行结果：

绘制文本

package com.example.pratice9;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.RectF;
import android.view.View;

public class MyView extends View {
    public MyView(Context context) {
        super(context);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        //绘制机器人
        //创建一个画笔
        Paint paint = new Paint();
        //采用抗锯齿功能
        paint.setAntiAlias(true);
        paint.setColor(0xFFA4C739);//设置画笔颜色为绿色

        //绘制机器人的头
        RectF rectF = new RectF(10,10,100,100);//定义外轮廓矩形
        rectF.offset(90,20);
        canvas.drawArc(rectF,-10,-160,false,paint);

        //绘制眼睛
        paint.setColor(0xFFFFFFFF);//设置画笔颜色为白色
        canvas.drawCircle(165,53,4,paint);
        canvas.drawCircle(125,53,4,paint);

        //绘制天线
        paint.setStrokeWidth(2);//设置笔触宽度
        paint.setColor(0xFFA4C739);
        canvas.drawLine(110,15,125,35,paint);
        canvas.drawLine(180,15,165,35,paint);

        //绘制身体
        canvas.drawRect(100,75,190,150,paint);//绘制矩形
        RectF rectF_body = new RectF(100,140,190,160);
        canvas.drawRoundRect(rectF_body,10,10,paint);

        //绘制胳膊
        RectF rectF_arm = new RectF(75,75,95,140);
        canvas.drawRoundRect(rectF_arm,10,10,paint);
        rectF_arm.offset(120,0);//调整偏移位置
        canvas.drawRoundRect(rectF_arm,10,10,paint);

        //绘制腿
        RectF rectF_leg = new RectF(115,150,135,200);
        canvas.drawRoundRect(rectF_leg,10,10,paint);
        rectF_leg.offset(40,0);//调整偏移位置
        canvas.drawRoundRect(rectF_leg,10,10,paint);
    }}

绘制图片

绘制路径

package com.example.pratice10;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.RectF;
import android.os.Environment;
import android.view.View;

public class MyView extends View {
    public MyView(Context context) {
        super(context);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        Paint paint = new Paint();
        paint.setAntiAlias(true);
        paint.setColor(0xFF0000FF);
        paint.setStyle(Paint.Style.STROKE);//设置填充样式为描边
        Path path = new Path();
        path.addCircle(550,500,150,Path.Direction.CW);//创建圆形路径
        canvas.drawPath(path,paint);
        //绘制绕路径的文本
        //paint.setTextSize(26);
        //canvas.drawTextOnPath("活着就是为了改变世界",path,0,0,paint);

    }
}

逐帧动画

补间动画

渐变

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Animation animation = AnimationUtils.
                        loadAnimation(MainActivity.this,R.anim.alpha);
                imageView.startAnimation(animation);//开启动画

旋转

Animation animation = AnimationUtils.
                        loadAnimation(MainActivity.this,R.anim.rotate);
                imageView.startAnimation(animation);//开启动画

缩放

Animation animation = AnimationUtils.
                        loadAnimation(MainActivity.this,R.anim.scale);
                imageView.startAnimation(animation);//开启动画

平移

Animation animation = AnimationUtils.
                        loadAnimation(MainActivity.this,R.anim.translate);
                imageView.startAnimation(animation);//开启动画