Android下利用Bitmap切割图片

亦凉 2022-07-24 09:26 194阅读 0赞

在自己自定义的一个组件中由于需要用图片显示数字编号，而当前图片就只有一张，上面有0-9是个数字，于是不得不考虑将其中一个个的数字切割下来，需要显示什么数字，只需要组合一下就好了。  
下面是程序的关键代码：  
在MyView（继承于View）类中的重写的onDraw(Canvas canvas)方法中，有如下代码段：

Bitmap resource = BitmapFactory.decodeResource(this.getResources(), R.drawable.num);  
            Bitmap zero = Bitmap.createBitmap(resource, 0, 0, 12, 12);  
            Bitmap one = Bitmap.createBitmap(resource, 12, 0, 12, 12);  
            Bitmap two = Bitmap.createBitmap(resource, 24, 0, 12, 12);  
            Bitmap three = Bitmap.createBitmap(resource, 36, 0, 12, 12);  
            Bitmap four = Bitmap.createBitmap(resource, 48, 0, 12, 12);  
            Bitmap five = Bitmap.createBitmap(resource, 60, 0, 12, 12);  
            Bitmap six = Bitmap.createBitmap(resource, 72, 0, 12, 12);  
            Bitmap seven = Bitmap.createBitmap(resource, 84, 0, 12, 12);  
            Bitmap eight = Bitmap.createBitmap(resource, 96, 0, 12, 12);  
            Bitmap nine = Bitmap.createBitmap(resource, 108, 0, 12, 12);

其中R.drawable.num为数字图片，每个数字占据的像素为12\*12，Bitmap.createBitmap方法中的五个参数意义分别为：需要切割的图片资源、切割起始点的X坐标、切割起始点的Y坐标、切割多宽、切割多高。  
切割下来之后就非常简单的就可以显示各种数字了，例如：用String类型的number表示需要显示的数字，则

char nums[] = number.toCharArray();  
            for(int i = 0; i < nums.length; i ++) {  
                if(nums[i] == '0') {  
                    canvas.drawBitmap(zero, i * 12, 0, mPaint);  
                } else if(nums[i] == '1') {  
                    canvas.drawBitmap(one, i * 12, 0, mPaint);  
                } else if(nums[i] == '2') {  
                    canvas.drawBitmap(two, i * 12, 0, mPaint);  
                } else if(nums[i] == '3') {  
                    canvas.drawBitmap(three, i * 12, 0, mPaint);  
                } else if(nums[i] == '4') {  
                    canvas.drawBitmap(four, i * 12, 0, mPaint);  
                } else if(nums[i] == '5') {  
                    canvas.drawBitmap(five, i * 12, 0, mPaint);  
                } else if(nums[i] == '6') {  
                    canvas.drawBitmap(six, i * 12, 0, mPaint);  
                } else if(nums[i] == '7') {  
                    canvas.drawBitmap(seven, i * 12, 0, mPaint);  
                } else if(nums[i] == '8') {  
                    canvas.drawBitmap(eight, i * 12, 0, mPaint);  
                } else if(nums[i] == '9') {  
                    canvas.drawBitmap(nine, i * 12, 0, mPaint);  
                }  
            }

其中canvas为画布，drawBitmap方法中的四个参数的意义分别为：需要绘制的图片资源、在画布上绘制的起始点的X坐标、Y坐标、画笔。其中画笔在此处可以不进行任何设置，只需new一个出来即可，Paint mPaint = new Paint();

### 完整代码 ###

### NumView ###

package com.barney;
    
    import android.content.Context;
    import android.graphics.Bitmap;
    import android.graphics.BitmapFactory;
    import android.graphics.Canvas;
    import android.graphics.Paint;
    import android.graphics.Rect;
    import android.util.DisplayMetrics;
    import android.view.View;
    
    public class NumView extends View {
        
        private static Paint mPaint;
        private String num;
    
        public NumView(Context context, String num) {
            super(context);
    
            this.num = num;
            mPaint = new Paint();
        }
    
        @Override
        public void draw(Canvas canvas) {
            super.onDraw(canvas);
    
            int base = 0;
            mPaint.setAntiAlias(true);
    
            DisplayMetrics dm = new DisplayMetrics();  
            dm = getResources().getDisplayMetrics(); 
            BitmapFactory.Options options = new BitmapFactory.Options();
            options.inDensity = dm.densityDpi;
    
            Bitmap resource = BitmapFactory.decodeResource(this.getResources(), R.drawable.num, options);
            Bitmap zero = Bitmap.createBitmap(resource, 0, 0, 12, 12);
            Bitmap one = Bitmap.createBitmap(resource, 12, 0, 12, 12);
            Bitmap two = Bitmap.createBitmap(resource, 24, 0, 12, 12);
            Bitmap three = Bitmap.createBitmap(resource, 36, 0, 12, 12);
            Bitmap four = Bitmap.createBitmap(resource, 48, 0, 12, 12);
            Bitmap five = Bitmap.createBitmap(resource, 60, 0, 12, 12);
            Bitmap six = Bitmap.createBitmap(resource, 72, 0, 12, 12);
            Bitmap seven = Bitmap.createBitmap(resource, 84, 0, 12, 12);
            Bitmap eight = Bitmap.createBitmap(resource, 96, 0, 12, 12);
            Bitmap nine = Bitmap.createBitmap(resource, 108, 0, 12, 12);
    
            char nums[] = num.toCharArray();
            for(int i = 0; i < nums.length; i ++) {
                Rect rect = new Rect();
                rect.set(base + i * 12, 0, base + i * 12 + 12, 12);
                Bitmap bitmap = null;
                if(nums[i] == '0') {
                    bitmap = zero;
                } else if(nums[i] == '1') {
                    bitmap = one;
                } else if(nums[i] == '2') {
                    bitmap = two;
                } else if(nums[i] == '3') {
                    bitmap = three;
                } else if(nums[i] == '4') {
                    bitmap = four;
                } else if(nums[i] == '5') {
                    bitmap = five;
                } else if(nums[i] == '6') {
                    bitmap = six;
                } else if(nums[i] == '7') {
                    bitmap = seven;
                } else if(nums[i] == '8') {
                    bitmap = eight;
                } else if(nums[i] == '9') {
                    bitmap = nine;
                }
    
                canvas.drawBitmap(bitmap,null, rect, mPaint);
            }
        }
    }

### BitmapDemoActivity ###

package com.barney;
    
    import android.app.Activity;
    import android.os.Bundle;
    import android.view.View;
    import android.view.View.OnClickListener;
    import android.widget.Button;
    import android.widget.EditText;
    import android.widget.LinearLayout;
    
    public class BitmapDemoActivity extends Activity {
        
    
        private EditText myEditText;
        private Button myButton;
        private LinearLayout myLinearLayout;
    
        /** Called when the activity is first created. */
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);
    
            myButton = (Button) this.findViewById(R.id.myButton);
            myEditText = (EditText) this.findViewById(R.id.myEditText);
            myLinearLayout = (LinearLayout) this.findViewById(R.id.myLinearLayout);
            myButton.setOnClickListener(new OnClickListener() {
    
                @Override
                public void onClick(View v) {
                    // TODO Auto-generated method stub
                    String num = myEditText.getText().toString();
                    NumView numView = new NumView(BitmapDemoActivity.this, num);
                    myLinearLayout.removeAllViews();
                    myLinearLayout.addView(numView);
                }
    
            });
        }
    }

### 源代码 ###

[源代码][Link 1]

### 参考链接 ###

[Android下利用Bitmap切割图片 - - ITeye技术网站][Android_Bitmap_ - - ITeye]

### 效果如下 ###

![这里写图片描述][20160519143931165]

[Link 1]: http://dl.iteye.com/topics/download/2bd62f21-86af-3759-a24f-de4002593751
[Android_Bitmap_ - - ITeye]: http://chen592969029.iteye.com/blog/749100
[20160519143931165]: /images/20220722/ab4f50aca91f48c0be405fdff1880964.png