How to realize Multi-Touch Application with android

This article introduces the relevant knowledge of "how to achieve multi-touch applications in android". Many people will encounter such a dilemma in the operation of actual cases, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

JhkMultiTouchActivity.java

Package com.android.forlinx; import android.app.Activity;import android.os.Bundle;import android.view.Window;import android.view.WindowManager; public class JhkMultiTouchActivity extends Activity {/ * * Called when the activity is first created. * / @ Override public void onCreate (Bundle savedInstanceState) {super.onCreate (savedInstanceState); / / setContentView (R.layout.main); / / hide title bar requestWindowFeature (Window.FEATURE_NO_TITLE) / / set to full screen getWindow () .setFlags (WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN); / / set to the above MTView setContentView (new MTView (this));}}

MTView.java

Package com.android.forlinx; import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.graphics.Typeface;import android.view.MotionEvent;import android.view.SurfaceHolder;import android.view.SurfaceView; public class MTView extends SurfaceView implements SurfaceHolder.Callback {private static final int MAX_TOUCHPOINTS = 10; private static final String START_TEXT = "feel free to touch the screen to test"; private Paint textPaint = new Paint () Private Paint touchPaints [] = new Paint [Max _ TOUCHPOINTS]; private int colors [] = new int [Max _ TOUCHPOINTS]; private int width, height; private float scale = 1.0f; public MTView (Context context) {super (context); SurfaceHolder holder = getHolder (); holder.addCallback (this); setFocusable (true); / / make sure our View gets input focus setFocusableInTouchMode (true) / / ensure that touch screen events init ();} private void init () {/ / initialize 10 different color brushes textPaint.setColor (Color.GREEN); textPaint.setTypeface (null); textPaint.setAlpha (200); colors [0] = Color.BLUE; colors [1] = Color.RED; colors [2] = Color.GREEN Colors [3] = Color.YELLOW; colors [4] = Color.CYAN; colors [5] = Color.MAGENTA; colors [6] = Color.DKGRAY; colors [7] = Color.WHITE; colors [8] = Color.LTGRAY; colors [9] = Color.GRAY; for (int I = 0; I

< MAX_TOUCHPOINTS; i++) { touchPaints[i] = new Paint(); touchPaints[i].setColor(colors[i]); touchPaints[i].setAlpha(50); } } /* * 处理触屏事件 */ @Override public boolean onTouchEvent(MotionEvent event) { // 获得屏幕触点数量 int pointerCount = event.getPointerCount(); if (pointerCount >

MAX_TOUCHPOINTS) {pointerCount = MAX_TOUCHPOINTS;} / / lock Canvas, start the corresponding interface processing Canvas c = getHolder () .lockCanvas (); if (c! = null) {c.drawColor (Color.BLACK) If (event.getAction () = = MotionEvent.ACTION_UP) {/ / when the hand leaves the screen, clear the screen} else {/ / draw a cross on the screen first, and then draw a circle for (int I = 0; I

< pointerCount; i++) { // 获取一个触点的坐标，然后开始绘制 int id = event.getPointerId(i); int x = (int) event.getX(i); int y = (int) event.getY(i); drawCrosshairsAndText(x, y, touchPaints[id], i, id, c); } for (int i = 0; i < pointerCount; i++) { int id = event.getPointerId(i); int x = (int) event.getX(i); int y = (int) event.getY(i); drawCircle(x, y, touchPaints[id], c); } } // 画完后，unlock getHolder().unlockCanvasAndPost(c); } return true; } /** * 画十字及坐标信息 * * @param x * @param y * @param paint * @param ptr * @param id * @param c */ private void drawCrosshairsAndText(int x, int y, Paint paint, int ptr, int id, Canvas c) { c.drawLine(0, y, width, y, paint); c.drawLine(x, 0, x, height, paint); int textY = (int) ((15 + 20 * ptr) * scale); c.drawText("x" + ptr + "=" + x, 10 * scale, textY, textPaint); c.drawText("y" + ptr + "=" + y, 70 * scale, textY, textPaint); c.drawText("id" + ptr + "=" + id, width - 55 * scale, textY, textPaint); } /** * 画圆 * * @param x * @param y * @param paint * @param c */ private void drawCircle(int x, int y, Paint paint, Canvas c) { c.drawCircle(x, y, 40 * scale, paint); } /* * 进入程序时背景画成黑色，然后把"START_TEXT"写到屏幕 */ public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { this.width = width; this.height = height; if (width >

Height) {this.scale = width / 480f;} else {this.scale = height / 480f;} textPaint.setTextSize (14 * scale); Canvas c = getHolder (). LockCanvas (); if (c! = null) {/ / background black c.drawColor (Color.BLACK); float tWidth = textPaint.measureText (START_TEXT) C.drawText (START_TEXT, width / 2-tWidth / 2, height / 2, textPaint); getHolder () .unlockCanvasAndPost (c);} public void surfaceCreated (SurfaceHolder holder) {} public void surfaceDestroyed (SurfaceHolder holder) {}}

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