android 矩阵坐标转换,使用矩阵旋转后，获得坐标的新位置_android_开发99编程知识库...

冷不防 2022-10-17 11:22 188阅读 0赞

我已經創建了一個簡單的演示。 它有一點額外的，所以你也可以看到如何在繪圖中使用它。

main.xml<?xml version="1.0" encoding="utf-8"?>

android:id="@+id/container"

android:layout\_width="fill\_parent"

android:layout\_height="fill\_parent">

android:id="@+id/seekBar1"

android:layout\_width="fill\_parent"

android:layout\_height="wrap\_content"

android:layout\_alignParentBottom="true"

android:layout\_centerHorizontal="true"/>

和 Activity:package nl.entreco.android.testrotation;

import android.app.Activity;

import android.content.Context;

import android.graphics.Canvas;

import android.graphics.Color;

import android.graphics.Matrix;

import android.graphics.Paint;

import android.graphics.Point;

import android.graphics.Rect;

import android.os.Bundle;

import android.util.Log;

import android.view.View;

import android.widget.RelativeLayout;

import android.widget.SeekBar;

import android.widget.SeekBar.OnSeekBarChangeListener;

public class RotationActivity extends Activity implements OnSeekBarChangeListener \{

private MyDrawing myDrawing;

private SeekBar mSeekbar;

/\*\* Called when the activity is first created. \*/

@Override

public void onCreate(Bundle savedInstanceState) \{

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

Rect rect = new Rect(150,150,440,630);

int x = (int) (rect.left + Math.random() \* rect.width());

int y = (int) (rect.top + Math.random() \* rect.height());

Point coordinate = new Point(x, y);

//To draw the rect we create a CustomView

myDrawing = new MyDrawing(this, rect, coordinate);

RelativeLayout rl = (RelativeLayout)findViewById(R.id.container);

rl.addView(myDrawing);

mSeekbar = (SeekBar)findViewById(R.id.seekBar1);

mSeekbar.setMax(360);

mSeekbar.setOnSeekBarChangeListener(this);

private class MyDrawing extends View

private Rect myRect;

private Point myPoint;

private Paint rectPaint;

private Paint pointPaint;

private Matrix transform;

public MyDrawing(Context context, Rect rect, Point point)

super(context);

//Store the Rect and Point

myRect = rect;

myPoint = point;

//Create Paint so we can see something :)

rectPaint = new Paint();

rectPaint.setColor(Color.GREEN);

pointPaint = new Paint();

pointPaint.setColor(Color.YELLOW);

//Create a matrix to do rotation

transform = new Matrix();

/\*\*

\* Add the Rotation to our Transform matrix.

\* A new point, with the rotated coordinates will be returned

\* @param degrees

\* @return

\*/

public Point rotate(float degrees)

//This is to rotate about the Rectangles center

transform.setRotate(degrees, myRect.exactCenterX(), myRect.exactCenterY());

//Create new float\[\] to hold the rotated coordinates

float\[\] pts = new float\[2\];

//Initialize the array with our Coordinate

pts\[0\] = myPoint.x;

pts\[1\] = myPoint.y;

//Use the Matrix to map the points

transform.mapPoints(pts);

//NOTE: pts will be changed by transform.mapPoints call

//after the call, pts will hold the new cooridnates

//Now, create a new Point from our new coordinates

Point newPoint = new Point((int)pts\[0\], (int)pts\[1\]);

//Return the new point

return newPoint;

@Override

public void onDraw(Canvas canvas)

if(myRect!= null && myPoint!= null)

//This is an easy way to apply the same transformation (e.g. rotation)

//To the complete canvas.

canvas.setMatrix(transform);

//With the Canvas being rotated, we can simply draw

//All our elements (Rect and Point)

canvas.drawRect(myRect, rectPaint);

canvas.drawCircle(myPoint.x, myPoint.y, 5, pointPaint);

@Override

public void onProgressChanged(SeekBar seekBar, int progress,boolean fromUser) \{

Point newCoordinates = myDrawing.rotate(progress);

//Now -> our float\[\] pts contains the new x,y coordinates

Log.d("test","Before Rotate myPoint("+newCoordinates.x+","+newCoordinates.y+")");

myDrawing.invalidate();

@Override

public void onStartTrackingTouch(SeekBar seekBar) \{\}

@Override

public void onStopTrackingTouch(SeekBar seekBar) \{\}

android 矩阵坐标转换,使用矩阵旋转后，获得坐标的新位置_android_开发99编程知识库...

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