Android（java）学习笔记183：多媒体之图形颜色的变化

1.相信大家都用过美图秀秀中如下的功能，调整颜色：

2. 下面通过案例说明Android中如何调色：

颜色矩阵 ColorMatrix cm = new ColorMatrix();

paint.setColorFilter(new ColorMatrixColorFilter(cm));

1 0 0 0 0

0 1 0 0 0

0 0 1 0 0

0 0 0 1 0

New Red Value = 1*128 + 0*128 + 0*128 + 0*0 + 0

New Blue Value = 0*128 + 1*128 + 0*128 + 0*0 + 0

New Green Value = 0*128 + 0*128 + 1*128 + 0*0 + 0

New Alpha Value = 0*128 + 0*128 + 0*128 + 1*0 + 0

（1）新建一个新的Android工程，如下：

（2）activity_main.xml，如下：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.himi.xiuxiu.MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="青------------->红" />

    <SeekBar
        android:id="@+id/sb_red"
        android:max="255"
        android:progress="128"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
     <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="紫------------->绿" />

    <SeekBar
        android:max="255"
        android:progress="128"
        android:id="@+id/sb_green"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
     <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="黄------------->蓝" />

    <SeekBar
        android:max="255"
        android:progress="128"
        android:id="@+id/sb_blue"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <ImageView 
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/iv"
        />

</LinearLayout>

其中控件SeekBar的属性android:max表示进度条的最大值，android:progress表示进度条的起初开始默认进度值

布局效果如下：

（3）MainActivity，如下：

package com.himi.xiuxiu;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.ColorMatrix;
import android.graphics.ColorMatrixColorFilter;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.os.Bundle;
import android.widget.ImageView;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;

public class MainActivity extends Activity implements OnSeekBarChangeListener {
    private SeekBar sb_red;
    private SeekBar sb_green;
    private SeekBar sb_blue;
    private ImageView iv;
    
    private Bitmap srcbitmap;
    private Bitmap alertbitmap;
    private Canvas canvas;
    private Paint paint;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        sb_red = (SeekBar) findViewById(R.id.sb_red);
        sb_green = (SeekBar) findViewById(R.id.sb_green);
        sb_blue = (SeekBar) findViewById(R.id.sb_blue);
        iv = (ImageView) findViewById(R.id.iv);
        //获得原图的位图
        srcbitmap = BitmapFactory.decodeResource(getResources(), R.drawable.pre19);
        //获得原图的拷贝副本
        alertbitmap = Bitmap.createBitmap(srcbitmap.getWidth(), srcbitmap.getHeight(), srcbitmap.getConfig());
        //创建一个画布
        canvas = new Canvas(alertbitmap);
        //创建画笔
        paint = new Paint();
        
        ColorMatrix cm = new ColorMatrix();
        cm.set(new float[] {
        1, 0, 0, 0, 0,
        0, 1, 0, 0, 0,
        0, 0, 1, 0, 0,
        0, 0, 0, 1, 0
        });
        
        paint.setColorFilter(new ColorMatrixColorFilter(cm));
        canvas.drawBitmap(srcbitmap, new Matrix(), paint);
        iv.setImageBitmap(alertbitmap);
        
        sb_red.setOnSeekBarChangeListener(this);
        sb_green.setOnSeekBarChangeListener(this);
        sb_blue.setOnSeekBarChangeListener(this);

    }
    public void onProgressChanged(SeekBar seekBar, int progress,
            boolean fromUser) {
        // TODO 自动生成的方法存根
        
    }
    public void onStartTrackingTouch(SeekBar seekBar) {
        // TODO 自动生成的方法存根
        
    }
    // 停止滑动进度条，才设置颜色变化，节省内存
    public void onStopTrackingTouch(SeekBar seekBar) {
        float red=1;
        float green=1;
        float blue=1;
        switch (seekBar.getId()) {
        case R.id.sb_red:
            red = seekBar.getProgress()/128.0f;
            break;
        case R.id.sb_green:
            green = seekBar.getProgress()/128.0f;
            break;
        case R.id.sb_blue:
            blue = seekBar.getProgress()/128.0f;
            break;

        default:
            break;
        }
        ColorMatrix cm = new ColorMatrix();
        cm.set(new float[] {    red, 0, 0, 0, 0,
                                0, green, 0, 0, 0,
                                0, 0, blue, 0, 0,
                                0, 0, 0, 1, 0 });
        
        paint.setColorFilter(new ColorMatrixColorFilter(cm));
        canvas.drawBitmap(srcbitmap, new Matrix(), paint);
        iv.setImageBitmap(alertbitmap);
    }

}

运行结果如下：