文章介紹了SurfaceView的用法。網(wǎng)上介紹SurfaceView的用法有很多，寫法也層出不同，例如繼承SurfaceView類，或者繼承SurfaceHolder.Callback類等，這個可以根據(jù)功能實際需要自己選擇，我這里就直接在普通的用戶界面調(diào)用SurfaceHolder的lockCanvas和unlockCanvasAndPost。
先來看看程序運行的截圖：
截圖1主要演示了直接把正弦波繪畫在SurfaceView上
對比上面的左右兩圖，右圖用.lockCanvas(null)，而左圖用.lockCanvas(new Rect(oldX, 0, oldX + length,
getWindowManager().getDefaultDisplay().getHeight()))，對比一下兩個效果，由于左圖是按指定Rect繪畫，所以效率會比右圖的全控件繪畫高些，并且在清屏之后(canvas.drawColor(Color.BLACK))不會留有上次繪畫的殘留。
接下來貼出main.xml的源碼:
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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent" android:layout_height="fill_parent"
android:orientation="vertical">
<LinearLayout android:id="@+id/LinearLayout01"
android:layout_width="wrap_content" android:layout_height="wrap_content">
<Button android:id="@+id/Button01" android:layout_width="wrap_content"
android:layout_height="wrap_content" android:text="簡單繪畫"></Button>
<Button android:id="@+id/Button02" android:layout_width="wrap_content"
android:layout_height="wrap_content" android:text="定時器繪畫"></Button>
</LinearLayout>
<SurfaceView android:id="@+id/SurfaceView01"
android:layout_width="fill_parent" android:layout_height="fill_parent"></SurfaceView>
</LinearLayout>
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent" android:layout_height="fill_parent"
android:orientation="vertical">
<LinearLayout android:id="@+id/LinearLayout01"
android:layout_width="wrap_content" android:layout_height="wrap_content">
<Button android:id="@+id/Button01" android:layout_width="wrap_content"
android:layout_height="wrap_content" android:text="簡單繪畫"></Button>
<Button android:id="@+id/Button02" android:layout_width="wrap_content"
android:layout_height="wrap_content" android:text="定時器繪畫"></Button>
</LinearLayout>
<SurfaceView android:id="@+id/SurfaceView01"
android:layout_width="fill_parent" android:layout_height="fill_parent"></SurfaceView>
</LinearLayout>
接下來貼出程序源碼：
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package com.testSurfaceView;
import java.util.Timer;
import java.util.TimerTask;
import android.app.Activity;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.os.Bundle;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;
public class testSurfaceView extends Activity {
/** Called when the activity is first created. */
Button btnSimpleDraw, btnTimerDraw;
SurfaceView sfv;
SurfaceHolder sfh;
private Timer mTimer;
private MyTimerTask mTimerTask;
int Y_axis[],//保存正弦波的Y軸上的點
centerY,//中心線
oldX,oldY,//上一個XY點
currentX;//當前繪制到的X軸上的點
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
btnSimpleDraw = (Button) this.findViewById(R.id.Button01);
btnTimerDraw = (Button) this.findViewById(R.id.Button02);
btnSimpleDraw.setOnClickListener(new ClickEvent());
btnTimerDraw.setOnClickListener(new ClickEvent());
sfv = (SurfaceView) this.findViewById(R.id.SurfaceView01);
sfh = sfv.getHolder();
//動態(tài)繪制正弦波的定時器
mTimer = new Timer();
mTimerTask = new MyTimerTask();
// 初始化y軸數(shù)據(jù)
centerY = (getWindowManager().getDefaultDisplay().getHeight() - sfv
.getTop()) / 2;
Y_axis = new int[getWindowManager().getDefaultDisplay().getWidth()];
for (int i = 1; i < Y_axis.length; i++) {// 計算正弦波
Y_axis[i - 1] = centerY
- (int) (100 * Math.sin(i * 2 * Math.PI / 180));
}
}
class ClickEvent implements View.OnClickListener {
@Override
public void onClick(View v) {
if (v == btnSimpleDraw) {
SimpleDraw(Y_axis.length-1);//直接繪制正弦波
} else if (v == btnTimerDraw) {
oldY = centerY;
mTimer.schedule(mTimerTask, 0, 5);//動態(tài)繪制正弦波
}
}
}
class MyTimerTask extends TimerTask {
@Override
public void run() {
SimpleDraw(currentX);
currentX++;//往前進
if (currentX == Y_axis.length - 1) {//如果到了終點，則清屏重來
ClearDraw();
currentX = 0;
oldY = centerY;
}
}
}
/*
* 繪制指定區(qū)域
*/
void SimpleDraw(int length) {
if (length == 0)
oldX = 0;
Canvas canvas = sfh.lockCanvas(new Rect(oldX, 0, oldX + length,
getWindowManager().getDefaultDisplay().getHeight()));// 關(guān)鍵:獲取畫布
Log.i("Canvas:",
String.valueOf(oldX) + "," + String.valueOf(oldX + length));
Paint mPaint = new Paint();
mPaint.setColor(Color.GREEN);// 畫筆為綠色
mPaint.setStrokeWidth(2);// 設(shè)置畫筆粗細
int y;
for (int i = oldX + 1; i < length; i++) {// 繪畫正弦波
y = Y_axis[i - 1];
canvas.drawLine(oldX, oldY, i, y, mPaint);
oldX = i;
oldY = y;
}
sfh.unlockCanvasAndPost(canvas);// 解鎖畫布，提交畫好的圖像
}
void ClearDraw() {
Canvas canvas = sfh.lockCanvas(null);
canvas.drawColor(Color.BLACK);// 清除畫布
sfh.unlockCanvasAndPost(canvas);
}
}
package com.testSurfaceView;
import java.util.Timer;
import java.util.TimerTask;
import android.app.Activity;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.os.Bundle;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;
public class testSurfaceView extends Activity {
/** Called when the activity is first created. */
Button btnSimpleDraw, btnTimerDraw;
SurfaceView sfv;
SurfaceHolder sfh;
private Timer mTimer;
private MyTimerTask mTimerTask;
int Y_axis[],//保存正弦波的Y軸上的點
centerY,//中心線
oldX,oldY,//上一個XY點
currentX;//當前繪制到的X軸上的點
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
btnSimpleDraw = (Button) this.findViewById(R.id.Button01);
btnTimerDraw = (Button) this.findViewById(R.id.Button02);
btnSimpleDraw.setOnClickListener(new ClickEvent());
btnTimerDraw.setOnClickListener(new ClickEvent());
sfv = (SurfaceView) this.findViewById(R.id.SurfaceView01);
sfh = sfv.getHolder();
//動態(tài)繪制正弦波的定時器
mTimer = new Timer();
mTimerTask = new MyTimerTask();
// 初始化y軸數(shù)據(jù)
centerY = (getWindowManager().getDefaultDisplay().getHeight() - sfv
.getTop()) / 2;
Y_axis = new int[getWindowManager().getDefaultDisplay().getWidth()];
for (int i = 1; i < Y_axis.length; i++) {// 計算正弦波
Y_axis[i - 1] = centerY
- (int) (100 * Math.sin(i * 2 * Math.PI / 180));
}
}
class ClickEvent implements View.OnClickListener {
@Override
public void onClick(View v) {
if (v == btnSimpleDraw) {
SimpleDraw(Y_axis.length-1);//直接繪制正弦波
} else if (v == btnTimerDraw) {
oldY = centerY;
mTimer.schedule(mTimerTask, 0, 5);//動態(tài)繪制正弦波
}
}
}
class MyTimerTask extends TimerTask {
@Override
public void run() {
SimpleDraw(currentX);
currentX++;//往前進
if (currentX == Y_axis.length - 1) {//如果到了終點，則清屏重來
ClearDraw();
currentX = 0;
oldY = centerY;
}
}
}
/*
* 繪制指定區(qū)域
*/
void SimpleDraw(int length) {
if (length == 0)
oldX = 0;
Canvas canvas = sfh.lockCanvas(new Rect(oldX, 0, oldX + length,
getWindowManager().getDefaultDisplay().getHeight()));// 關(guān)鍵:獲取畫布
Log.i("Canvas:",
String.valueOf(oldX) + "," + String.valueOf(oldX + length));
Paint mPaint = new Paint();
mPaint.setColor(Color.GREEN);// 畫筆為綠色
mPaint.setStrokeWidth(2);// 設(shè)置畫筆粗細
int y;
for (int i = oldX + 1; i < length; i++) {// 繪畫正弦波
y = Y_axis[i - 1];
canvas.drawLine(oldX, oldY, i, y, mPaint);
oldX = i;
oldY = y;
}
sfh.unlockCanvasAndPost(canvas);// 解鎖畫布，提交畫好的圖像
}
void ClearDraw() {
Canvas canvas = sfh.lockCanvas(null);
canvas.drawColor(Color.BLACK);// 清除畫布
sfh.unlockCanvasAndPost(canvas);
}
}
注意一下 for (int i = oldX + 1; i < length; i++) {// 繪畫正弦波 這句，在.lockCanvas()指定Rect內(nèi)減少循環(huán)畫線的次數(shù)，可以提高繪圖效率。
(審核編輯: 智匯小新)
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