Android（java）学习笔记240：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：