Android中“用放大鏡效果查看圖庫(kù)中的圖”的代碼清單

1、Android中“用放大鏡效果查看圖庫(kù)中的圖”的代碼清單范美英（北京信息職業(yè)技術(shù)學(xué)院）摘 要：Android中可以自定義視圖，只需要將視圖類繼承自View，并重寫其onDraw方法即可。本文詳細(xì)羅列了Android應(yīng)用界面中自定義視圖，并“用放大鏡效果查看圖庫(kù)中的圖”的代碼清單。關(guān)鍵詞： Android；自定義視圖；圖庫(kù) 1 src/MainActivity.java類的代碼package com.book.testmagnifyphoto;import android.app.Activity;import android.content.Intent;import android.data

2、base.Cursor;import .Uri;import android.os.Bundle;import vider.MediaStore;import android.view.View;public class MainActivity extends Activity /定義請(qǐng)求碼private static final int ChooseImage = 1;/聲明MagnifyView對(duì)象MagnifyView imgChosen;Overrideprotected void onCreate(Bundle savedInstanceState) supe

3、r.onCreate(savedInstanceState);this.setContentView(R.layout.activity_main);imgChosen = (MagnifyView) findViewById(R.id.img_chosen);public void clickChoose(View v)/啟動(dòng)圖庫(kù)activity，并帶回選擇的圖片Intent i = new Intent(Intent.ACTION_PICK, vider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);startActivi

4、tyForResult(i, ChooseImage);Overrideprotected void onActivityResult(int requestCode, int resultCode, Intent data) super.onActivityResult(requestCode, resultCode, data);/如果正確選擇了圖片if (requestCode = ChooseImage && resultCode = RESULT_OK && data != null) /獲取選擇的圖片 Uri selectedImage = data

5、.getData(); String filePathColumn = MediaStore.Images.Media.DATA ; Cursor cursor = getContentResolver().query( selectedImage, filePathColumn, null, null, null); cursor.moveToFirst(); int columnIndex = cursor.getColumnIndex(filePathColumn0); String picturePath = cursor.getString(columnIndex); cursor.

6、close(); if(picturePath!=null) imgChosen.setBitmap(picturePath); 2 src/ MagnifyView.java類的代碼package com.book.testmagnifyphoto;import android.content.Context;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.BitmapShader;import android.graphics.Canvas;import

7、 android.graphics.Matrix;import android.graphics.Shader.TileMode;import android.graphics.drawable.ShapeDrawable;import android.graphics.drawable.shapes.OvalShape;import android.util.AttributeSet;import android.util.Log;import android.view.MotionEvent;import android.view.View;public class MagnifyView

8、 extends View / 從圖庫(kù)中獲取到的圖像private Bitmap bitmap; / 放大后的圓形遮罩private ShapeDrawable drawable;/ 放大鏡的半徑，隨著分辨率的不同會(huì)發(fā)生改變private final int RADIUS = 38; / 放大倍數(shù)private final int FACTOR = 2; private Matrix matrix = new Matrix();/ 放大鏡位圖private Bitmap bitmap_magnifier; / 放大鏡的左邊距private int m_left = 0; / 放大鏡的頂邊距pr

9、ivate int m_top = 0;/ 構(gòu)造函數(shù)public MagnifyView(Context context, AttributeSet as) super(context,as);/獲取放大鏡圖像bitmap_magnifier = BitmapFactory.decodeResource(getResources(),R.drawable.magnifier);Overrideprotected void onDraw(Canvas canvas) super.onDraw(canvas);try/ 繪制居中的背景圖像canvas.drawBitmap(bitmap, (get

10、Width()-bitmap.getWidth()/2, (getHeight()-bitmap.getHeight()/2, null); / 繪制放大后的圖像drawable.draw(canvas); catch(Exception e)e.getCause();/ 繪制放大鏡canvas.drawBitmap(bitmap_magnifier, m_left, m_top, null);Overridepublic boolean onTouchEvent(MotionEvent event) / 獲取當(dāng)前觸摸點(diǎn)的橫坐標(biāo)final int x = (int) event.getX();

11、 / 獲取當(dāng)前觸摸點(diǎn)的縱坐標(biāo)final int y = (int) event.getY(); try/ 平移到繪制shader的起始位置/ 水平方向平移RADIUS - x * FACTOR，垂直方向平移RADIUS - y * FACTORmatrix.setTranslate(RADIUS - x * FACTOR, RADIUS - y * FACTOR );drawable.getPaint().getShader().setLocalMatrix(matrix);/ 設(shè)置圓的外切矩形，以此觸發(fā)drawable的繪制drawable.setBounds(x - RADIUS, y -

12、 RADIUS, x + RADIUS, y + RADIUS);catch(Exception e)e.getCause();/ 計(jì)算放大鏡的左邊距m_left = x - bitmap_magnifier.getWidth() / 2; / 計(jì)算放大鏡的右邊距m_top = y - bitmap_magnifier.getHeight() / 2; invalidate(); / 重繪畫布return true;/獲取要顯示的源圖，并放大圖public void setBitmap(String picturePath) /取得源圖bitmap= BitmapFactory.decodeF

13、ile(picturePath);/根據(jù)畫布寬、高縮放源圖bitmap= bitmap.createScaledBitmap(bitmap, getWidth(), getHeight(), true);/以FACTOR為倍數(shù)放大圖magnifyBitmap(bitmap,FACTOR);/生成放大效果圖private void magnifyBitmap(Bitmap bitmap, int factor) / TODO Auto-generated method stub/放大后的圖BitmapShader shader = new BitmapShader(Bitmap.createSc

14、aledBitmap(bitmap, bitmap.getWidth() * factor,bitmap.getHeight() * factor, true), TileMode.CLAMP,TileMode.CLAMP);/ 圓形遮罩drawable = new ShapeDrawable(new OvalShape();/ 將放大后的圖切除多余部分后放到drawable中drawable.getPaint().setShader(shader);/ 設(shè)置圓的外切矩形，以此觸發(fā)drawable的繪制drawable.setBounds(0, 0, RADIUS * 2, RADIUS *

15、2); / 此處計(jì)算放大鏡的邊距可以使得遮罩和放大鏡初始位置相同m_left = RADIUS - bitmap_magnifier.getWidth() / 2; m_top = RADIUS - bitmap_magnifier.getHeight() / 2; 3 res/layout/activity_main.xml的代碼清單<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android=" android:layout_width="ma

16、tch_parent" android:layout_height="match_parent" android:orientation="vertical" > <com.book.testmagnifyphoto.MagnifyView android:id="+id/img_chosen" android:layout_width="match_parent" android:layout_height="0dp" android:layout_weight="9"/> <Button android:id="+id/btn_choose" android:la