Android通过手势实现的缩放处理

02

import

android.content.Context;

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import

android.graphics.Canvas;

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import

android.graphics.Color;

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import

android.graphics.Paint;

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import

android.os.Bundle;

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import

android.util.DisplayMetrics;

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import

android.view.MotionEvent;

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import

android.view.View;

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/**

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*
...

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*

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*
@authorvlinux

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*

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*/

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public

class

MultiTouchTestActivity

extends

Activity
{

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/**
Calledwhentheactivityisfirstcreated.*/

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@Override

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public

void

onCreate(Bundle
savedInstanceState){

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super

.onCreate(savedInstanceState);

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//
setContentView(R.layout.main);

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View
view=

new

MultiTouchView(

this

);

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setContentView(view);

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}

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class

MultiTouchView

extends

View
{

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private

float

x1;

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private

float

y1;

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private

float

x2;

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private

float

y2;

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public

MultiTouchView(Context
context){

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super

(context);

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//
TODOAuto-generatedconstructorstub

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}

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@Override

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public

boolean

onTouchEvent(MotionEvent
event){

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//
TODOAuto-generatedmethodstub

42

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float

size
=event.getSize();

44

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int

szi
=(

int

)
size;

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int

dxi
=szi>>

12

;

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int

dyit
=((

1

<<

12

)
-

1

);

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int

dyi
=szi&dyit;

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DisplayMetrics
metrics=getResources().getDisplayMetrics();

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float

dx
=metrics.widthPixels*dxi/(

float

)
dyit;

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float

dy
=metrics.heightPixels*dyi/(

float

)
dyit;

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x1
=event.getX();

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y1
=event.getY();

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x2
=x1+dx;

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y2
=y1+dy;

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invalidate();

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return

true

;

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}

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@Override

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protected

void

onDraw(Canvas
canvas){

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//
TODOAuto-generatedmethodstub

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super

.onDraw(canvas);

69

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float

r
=(

float

)
Math.sqrt((x1-x2)*(x1-x2)+(y1-y2)

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*
(y1-y2))/

2

;

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r
=

50

>=
r?

50

:
r;

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Paint
paint=

new

Paint();

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paint.setColor(Color.BLUE);

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canvas.drawCircle(x1,
y1,r,paint);

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}

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}

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}