【移动应用开发技术】Android中怎么实现多点触摸

【移动应用开发技术】Android中怎么实现多点触摸

Android中怎么实现多点触摸，针对这个问题，这篇文章详细介绍了相对应的分析和解答，希望可以帮助更多想解决这个问题的小伙伴找到更简单易行的方法。首先来看看我们的视图类MTView.java:package

com.ideasandroid.demo;

import

android.content.Context;

import

android.graphics.Canvas;

import

android.graphics.Color;

import

android.graphics.Paint;

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

=

"请随便触摸屏幕进行测试";

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);

//

确保我们的View能获得输入焦点

setFocusableInTouchMode(true);

//

确保能接收到触屏事件

init();

}

private

void

init()

{

//

初始化10个不同颜色的画笔

textPaint.setColor(Color.WHITE);

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]);

}

}

/*

*

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;

}

//

锁定Canvas,开始进行相应的界面处理

Canvas

c

=

getHolder().lockCanvas();

if

(c

!=

null)

{

c.drawColor(Color.BLACK);

if

(event.getAction()

==

MotionEvent.ACTION_UP)

{

//

当手离开屏幕时，清屏

}

else

{

//

先在屏幕上画一个十字，然后画一个圆

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,

intwidth,

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)

{

//

背景黑色

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)

{

}

}接下来看看我们的Activity，MultitouchVisible.javapackage

com.ideasandroid.demo;

import

android.app.Activity;

import

android.os.Bundle;

import

android.view.Window;

import

android.view.WindowManager;

public

class

MultitouchVisible

extends

Activity

{

@Override

public

void

onCreate(Bundle

savedInstanceState)

{

super.onCreate(savedInstanceState);

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