我有一个360度旋转的密码锁。
组合锁上有数值，这些都是纯粹的图形。
我需要一种方法将图像的旋转转换为图形上的0-99值。
在第一张图中，该值应该能够告诉我“0”
http://i48.tinypic.com/27y67b7.png
在此图中，用户旋转图像后，该值应该能够告诉我“72”
http://i46.tinypic.com/2ueiogh.png
以下是代码：
package co.sts.combinationlock;
import android.os.Bundle;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.util.Log;
import android.view.GestureDetector;
import android.view.Menu;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.View;
import android.view.GestureDetector.SimpleOnGestureListener;
import android.view.View.OnTouchListener;
import android.view.ViewTreeObserver.OnGlobalLayoutListener;
import android.widget.ImageView;
import android.support.v4.app.NavUtils;
public class ComboLock extends Activity{
private static Bitmap imageOriginal, imageScaled;
private static Matrix matrix;
private ImageView dialer;
private int dialerHeight, dialerWidth;
private GestureDetector detector;
// needed for detecting the inversed rotations
private boolean[] quadrantTouched;
private boolean allowRotating;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_combo_lock);
// load the image only once
if (imageOriginal == null) {
imageOriginal = BitmapFactory.decodeResource(getResources(), R.drawable.numbers);
}
// initialize the matrix only once
if (matrix == null) {
matrix = new Matrix();
} else {
// not needed, you can also post the matrix immediately to restore the old state
matrix.reset();
}
detector = new GestureDetector(this, new MyGestureDetector());
// there is no 0th quadrant, to keep it simple the first value gets ignored
quadrantTouched = new boolean[] { false, false, false, false, false };
allowRotating = true;
dialer = (ImageView) findViewById(R.id.locknumbers);
dialer.setOnTouchListener(new MyOnTouchListener());
dialer.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
// method called more than once, but the values only need to be initialized one time
if (dialerHeight == 0 || dialerWidth == 0) {
dialerHeight = dialer.getHeight();
dialerWidth = dialer.getWidth();
// resize
Matrix resize = new Matrix();
//resize.postScale((float)Math.min(dialerWidth, dialerHeight) / (float)imageOriginal.getWidth(), (float)Math.min(dialerWidth, dialerHeight) / (float)imageOriginal.getHeight());
imageScaled = Bitmap.createBitmap(imageOriginal, 0, 0, imageOriginal.getWidth(), imageOriginal.getHeight(), resize, false);
// translate to the image view's center
float translateX = dialerWidth / 2 - imageScaled.getWidth() / 2;
float translateY = dialerHeight / 2 - imageScaled.getHeight() / 2;
matrix.postTranslate(translateX, translateY);
dialer.setImageBitmap(imageScaled);
dialer.setImageMatrix(matrix);
}
}
});
}
/**
* Rotate the dialer.
*
* @param degrees The degrees, the dialer should get rotated.
*/
private void rotateDialer(float degrees) {
matrix.postRotate(degrees, dialerWidth / 2, dialerHeight / 2);
//need to print degrees
dialer.setImageMatrix(matrix);
}
/**
* @return The angle of the unit circle with the image view's center
*/
private double getAngle(double xTouch, double yTouch) {
double x = xTouch - (dialerWidth / 2d);
double y = dialerHeight - yTouch - (dialerHeight / 2d);
switch (getQuadrant(x, y)) {
case 1:
return Math.asin(y / Math.hypot(x, y)) * 180 / Math.PI;
case 2:
case 3:
return 180 - (Math.asin(y / Math.hypot(x, y)) * 180 / Math.PI);
case 4:
return 360 + Math.asin(y / Math.hypot(x, y)) * 180 / Math.PI;
default:
// ignore, does not happen
return 0;
}
}
/**
* @return The selected quadrant.
*/
private static int getQuadrant(double x, double y) {
if (x >= 0) {
return y >= 0 ? 1 : 4;
} else {
return y >= 0 ? 2 : 3;
}
}
/**
* Simple implementation of an {@link OnTouchListener} for registering the dialer's touch events.
*/
private class MyOnTouchListener implements OnTouchListener {
private double startAngle;
@Override
public boolean onTouch(View v, MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
// reset the touched quadrants
for (int i = 0; i < quadrantTouched.length; i++) {
quadrantTouched[i] = false;
}
allowRotating = false;
startAngle = getAngle(event.getX(), event.getY());
break;
case MotionEvent.ACTION_MOVE:
double currentAngle = getAngle(event.getX(), event.getY());
rotateDialer((float) (startAngle - currentAngle));
startAngle = currentAngle;
break;
case MotionEvent.ACTION_UP:
allowRotating = true;
break;
}
// set the touched quadrant to true
quadrantTouched[getQuadrant(event.getX() - (dialerWidth / 2), dialerHeight - event.getY() - (dialerHeight / 2))] = true;
detector.onTouchEvent(event);
return true;
}
}
/**
* Simple implementation of a {@link SimpleOnGestureListener} for detecting a fling event.
*/
private class MyGestureDetector extends SimpleOnGestureListener {
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
// get the quadrant of the start and the end of the fling
int q1 = getQuadrant(e1.getX() - (dialerWidth / 2), dialerHeight - e1.getY() - (dialerHeight / 2));
int q2 = getQuadrant(e2.getX() - (dialerWidth / 2), dialerHeight - e2.getY() - (dialerHeight / 2));
// the inversed rotations
if ((q1 == 2 && q2 == 2 && Math.abs(velocityX) < Math.abs(velocityY))
|| (q1 == 3 && q2 == 3)
|| (q1 == 1 && q2 == 3)
|| (q1 == 4 && q2 == 4 && Math.abs(velocityX) > Math.abs(velocityY))
|| ((q1 == 2 && q2 == 3) || (q1 == 3 && q2 == 2))
|| ((q1 == 3 && q2 == 4) || (q1 == 4 && q2 == 3))
|| (q1 == 2 && q2 == 4 && quadrantTouched[3])
|| (q1 == 4 && q2 == 2 && quadrantTouched[3])) {
dialer.post(new FlingRunnable(-1 * (velocityX + velocityY)));
} else {
// the normal rotation
dialer.post(new FlingRunnable(velocityX + velocityY));
}
return true;
}
}
/**
* A {@link Runnable} for animating the the dialer's fling.
*/
private class FlingRunnable implements Runnable {
private float velocity;
public FlingRunnable(float velocity) {
this.velocity = velocity;
}
@Override
public void run() {
if (Math.abs(velocity) > 5 && allowRotating) {
//rotateDialer(velocity / 75);
//velocity /= 1.0666F;
// post this instance again
dialer.post(this);
}
}
}
}
我想我需要将矩阵中的一些信息转换为0-99值。
答案 0 :(得分：8)
您应该完全重新组织代码。将新的旋转一次又一次地乘以矩阵后是数值上不稳定的计算。最终位图将变形。试图从矩阵中检索旋转角度太复杂且不必要。
首先请注意，this是关于绘制位图的有用的先前文章，其中包含围绕所选点的旋转。
只需保持一个double dialAngle = 0即表盘的当前旋转角度。
您正在做太多的工作来从触摸位置检索角度。让(x0,y0)成为触摸开始的位置。那时，
// Record the angle at initial touch for use in dragging.
dialAngleAtTouch = dialAngle;
// Find angle from x-axis made by initial touch coordinate.
// y-coordinate might need to be negated due to y=0 -> screen top.
// This will be obvious during testing.
a0 = Math.atan2(y0 - yDialCenter, x0 - xDialCenter);
这是起始角度。当触摸拖动到(x,y)时，使用此坐标相对于初始触摸调整刻度盘。然后更新矩阵并重绘：
// Find new angle to x-axis. Same comment as above on y coord.
a = Math.atan2(y - yDialCenter, x - xDialCenter);
// New dial angle is offset from the one at initial touch.
dialAngle = dialAngleAtTouch + (a - a0);
// normalize angles to the interval [0..2pi)
while (dialAngle < 0) dialAngle += 2 * Math.PI;
while (dialAngle >= 2 * Math.PI) dialAngle -= 2 * Math.PI;
// Set the matrix for every frame drawn. Matrix API has a call
// for rotation about a point. Use it!
matrix.setRotate((float)dialAngle * (180 / 3.1415926f), xDialCenter, yDialCenter);
// Invalidate the view now so it's redrawn in with the new matrix value.
注意Math.atan2(y, x)完成你使用象限和反正弦所做的所有事情。
要获得当前角度的“滴答”，你需要2 pi的弧度来对应100，所以它非常简单：
double fractionalTick = dialAngle / (2 * Math.Pi) * 100;
要将实际最接近的刻度值作为整数查找，请将分数和mod四舍五入。注意您可以忽略矩阵！
int tick = (int)(fractionalTick + 0.5) % 100;
这将始终有效，因为dialAngle位于[0..2pi]。需要mod来将舍入值100映射回0。
答案 1 :(得分：5)
为了更好地理解矩阵的作用，理解2d图形变换矩阵是有帮助的：http://en.wikipedia.org/wiki/Transformation_matrix#Examples_in_2D_graphics。如果您正在做的唯一事情是旋转（不是，比如变换或缩放），则提取旋转相对容易。但是，更实际的是，您可以修改旋转代码，并存储状态变量
private float rotationDegrees = 0;
/**
* Rotate the dialer.
*
* @param degrees The degrees, the dialer should get rotated.
*/
private void rotateDialer(float degrees)
matrix.postRotate(degrees, dialerWidth / 2, dialerHeight / 2);
this.rotationDegrees += degrees;
// Make sure we don't go over 360
this.rotationDegrees = this.rotationDegrees % 360
dialer.setImageMatrix(matrix);
}
保留一个变量来存储以旋转度为单位递增的总旋转度。现在，我们知道3.6度是一个刻度。简单的数学运算
tickNumber = (int)rotation*100/360
// It could be negative
if (tickNumber < 0)
tickNumber = 100 - tickNumber
你需要检查的最后一件事：如果旋转完全 360度，或者刻度数为100，你必须将其视为0（因为没有刻度线） 100）
答案 2 :(得分：4)
这应该是一个简单的乘法，带有“比例”因子，可以将你的学位值（0-359）缩小到你的0-99比例：
float factor = 99f / 359f;
float scaled = rotationDegree * factor;
编辑：更正getAngle函数
对于getAngle，您可以使用atan2函数，将笛卡尔坐标转换为角度。
只需在触摸下方存储第一个触摸坐标，然后在移动时可以应用以下计算：
// PointF a = touch start point
// PointF b = current touch move point
// Translate to origin:
float x = b.x - a.x;
float y = b.y - a.y;
float radians = (float) ((Math.atan2(-y, x) + Math.PI + HALF_PI) % TWO_PI);
弧度范围为两个pi。模数计算将其旋转，因此值为0。旋转方向是逆时针方向。
因此您需要将其转换为度数并更改旋转方向以获得正确的角度。
答案 3 :(得分：2)
表盘应旋转3.6度，从一个标记转到下一个或上一个标记。 每当用户的触摸旋转（围绕中心）3.6度时，表盘应旋转1个标记（3.6度）。
代码段：
float touchAngle = getTouchAngle();
float mark = touchAngle / 3.6f;
if (mCurrentMark != mark) {
setDialMark(mark);
}
getTouchAngle()使用atan2计算用户触摸点与中心拨号的角度。setDialMark通过更改的标记数旋转表盘。
void setDialMark(int mark) {
rotateDialBy(mCurrentMark - mark);
mCurrentMark = mark;
}
void rotateDialBy(int rotateMarks) {
rotationAngle = rotateMarks * 3.6;
...
/* Rotate the dial by rotationAngle. */
}