【移動(dòng)應(yīng)用開發(fā)技術(shù)】如何在android中使用Path繪制一個(gè)多邊形

【移動(dòng)應(yīng)用開發(fā)技術(shù)】如何在android中使用Path繪制一個(gè)多邊形

今天就跟大家聊聊有關(guān)如何在android中使用Path繪制一個(gè)多邊形，可能很多人都不太了解，為了讓大家更加了解，在下給大家總結(jié)了以下內(nèi)容，希望大家根據(jù)這篇文章可以有所收獲。package

.pathview;

import

android.content.Context;

import

android.graphics.Canvas;

import

android.graphics.Color;

import

android.graphics.Paint;

import

android.util.AttributeSet;

import

android.view.View;

/**

*

繪制多邊形

*/

public

class

PathmMultiView

extends

View

{

private

Paint

paint;

public

PathmMultiView(Context

context)

{

this(context,null);

}

public

PathmMultiView(Context

context,

AttributeSet

attrs)

{

this(context,

attrs,0);

}

public

PathmMultiView(Context

context,

AttributeSet

attrs,

int

defStyleAttr)

{

super(context,

attrs,

defStyleAttr);

initPaint();

}

private

void

initPaint()

{

paint

=

new

Paint();

paint.setAntiAlias(true);

paint.setStrokeWidth(5);

paint.setTextSize(24);

}

@Override

protected

void

onDraw(Canvas

canvas)

{

super.onDraw(canvas);

paint.setColor(Color.GREEN);

canvas.drawText("杭州是個(gè)美麗的城市",20,20,paint);

paint.setColor(Color.RED);

canvas.drawPoint(100,100,paint);

canvas.translate(100,100);

paint.setColor(Color.BLUE);

canvas.drawText("杭州是個(gè)美麗的城市",0,0,paint);

}

}效果：上面的紅點(diǎn)是坐標(biāo)點(diǎn)(100,100)的位置,為什么繪制的藍(lán)色的文字是在坐標(biāo)點(diǎn)(100,100)的位置呢?是因?yàn)槟鉩anvas使用了translate(100,100)也就是x,y坐標(biāo)都平移了100px,這個(gè)是根據(jù)你當(dāng)前的view的左上角坐標(biāo)為原點(diǎn)進(jìn)行平移的,平移肯定是相對(duì)那個(gè)點(diǎn)進(jìn)行平移的,不人為的去設(shè)置畫布的顏色,默認(rèn)都是透明的,否則你draw...2次,上次繪制的內(nèi)容就被覆蓋了,文字太蒼白無(wú)力,就好像你對(duì)一個(gè)女孩說一千篇我愛你,還不如說你在杭州買了套房來(lái)的實(shí)際,就好像香港有一個(gè)電影中的臺(tái)詞是這么說的,這是一個(gè)最好的時(shí)代,也是一個(gè)最壞的時(shí)代,好了廢話不多說,圖,我要圖!關(guān)于如何恢復(fù)畫布有三種情況就以平移例子來(lái)講第一種：你x,y平移了多少后,我們知道x>0是向右平移,x<0是向左平移,那么恢復(fù)就很簡(jiǎn)單了canvas.translate(-x,-y)@Override

protected

void

onDraw(Canvas

canvas)

{

super.onDraw(canvas);

paint.setColor(Color.GREEN);

canvas.drawText("杭州是個(gè)美麗的城市",20,20,paint);

paint.setColor(Color.RED);

canvas.drawPoint(100,100,paint);

canvas.translate(100,100);

paint.setColor(Color.BLUE);

canvas.translate(-100,-100);

canvas.drawText("杭州是個(gè)美麗的城市",20,20,paint);

}效果：你會(huì)發(fā)現(xiàn)綠色和藍(lán)色是重疊了。第二種：配套使用canvas.save()canvas.restore();save()是綁定畫布,restore()是讓畫布恢復(fù)到最初的狀態(tài)@Override

protected

void

onDraw(Canvas

canvas)

{

super.onDraw(canvas);

paint.setColor(Color.GREEN);

canvas.save();

canvas.drawText("杭州是個(gè)美麗的城市",20,20,paint);

paint.setColor(Color.RED);

canvas.drawPoint(100,100,paint);

canvas.translate(100,100);

paint.setColor(Color.BLUE);

canvas.restore();

canvas.drawText("杭州是個(gè)美麗的城市",20,20,paint);

}效果：第三種：int

count

=

canvas.save(Canvas.MATRIX_SAVE_FLAG);//這個(gè)看你是在canvas.draw...哪里調(diào)用了,就相當(dāng)于保存畫布

canvas.restoreToCount(count);//恢復(fù)畫圖：現(xiàn)在講下畫多邊形,先確定下思路：1:把這個(gè)多邊形的外切圓畫出來(lái)當(dāng)做一個(gè)輔助的參考目標(biāo),2:計(jì)算多個(gè)點(diǎn)的坐標(biāo)然后連接成一條線如圖分析：現(xiàn)在根據(jù)這個(gè)思路把代碼實(shí)現(xiàn)下：代碼如下：package

.pathview;

import

android.content.Context;

import

android.graphics.Canvas;

import

android.graphics.Color;

import

android.graphics.Paint;

import

android.graphics.Path;

import

android.util.AttributeSet;

import

android.view.View;

/**

*

繪制多邊形

*/

public

class

PathmMultiView

extends

View

{

private

Paint

paint;

private

Path

path;

private

int

width,height;

public

PathmMultiView(Context

context)

{

this(context,null);

}

public

PathmMultiView(Context

context,

AttributeSet

attrs)

{

this(context,

attrs,0);

}

public

PathmMultiView(Context

context,

AttributeSet

attrs,

int

defStyleAttr)

{

super(context,

attrs,

defStyleAttr);

initPaint();

}

private

void

initPaint()

{

width

=

400;

height

=

400;

path

=

new

Path();

paint

=

new

Paint();

paint.setAntiAlias(true);

paint.setStrokeWidth(5);

paint.setColor(Color.BLUE);

paint.setStyle(Paint.Style.STROKE);

}

@Override

protected

void

onMeasure(int

widthMeasureSpec,

int

heightMeasureSpec)

{

setMeasuredDimension(width,height);

}

@Override

protected

void

onDraw(Canvas

canvas)

{

super.onDraw(canvas);

drawMultShape(canvas,6,width/2);

}

/**

*

@param

canvas

畫布

*

@param

count

繪制幾邊形

*

@param

radius

//外圓的半徑

*/

public

void

drawMultShape(Canvas

canvas,int

count,float

radius){

canvas.translate(radius,radius);//

if(count<5){

return;

}

for

(int

i=0;i<count;i++){

if

(i==0){

path.moveTo(radius*cos(360/count*i),radius*sin(360/count*i));//繪制起點(diǎn)

}else{

path.lineTo(radius*cos(360/count*i),radius*sin(360/count*i));

}

}

paint.setStrokeWidth(3);

path.close();

paint.setColor(Color.GREEN);

canvas.drawPath(path,paint);

//因?yàn)槲蚁旅娌辉倮L制內(nèi)容了

所以畫布就不恢復(fù)了

}

float

sin(int

num){

return

(float)

Math.sin(num*Math.PI/180);

}

float

cos(int

num){

return

(float)

Math.cos(num*Math.PI/180);

}

}效果：哪繪制正8變形呢?好說,