我正在开发 Canvas 应用程序，我创建了一个带有颜色选择器、撤消、重做和清除功能的 Canvas ，它也工作正常。现在，我想验证用户当前是否在背景线上绘制一条线在 Canvas 上。
例如， 我有一个带虚线的背景图像，现在我想让用户在虚线上画画，我必须验证它是否正确？是否可以在 canvas 中使用？我该如何处理？
有人可以就此提出任何建议，这将真正帮助我继续我的应用程序的下一步，我的代码在这里，
public class HomeScreen extends Activity implements ColorPickerDialog.OnColorChangedListener {
public int width;
public int height;
public Arrays paths1;
private Bitmap mBitmap;
private Canvas mCanvas;
private Path mPath;
private Paint mBitmapPaint;
Context context;
private Paint circlePaint;
private Path circlePath;
/* MyView mv; */
DrawingPanel dp;
AlertDialog dialog;
private ArrayList<Path> undonePaths = new ArrayList<Path>();
private ArrayList<Path> paths = new ArrayList<Path>();
FrameLayout frmLayout;
Canvas canvas;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home_screen);
dp = new DrawingPanel(this);
frmLayout = (FrameLayout) findViewById(R.id.frameLayout);
frmLayout.addView(dp);
((Button) findViewById(R.id.Clear)).setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
paths = new ArrayList<Path>();
if (paths != null)
paths.clear();
if (dp != null)
dp.invalidate();
}
});
((Button) findViewById(R.id.Undo)).setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if (paths.size() > 0) {
undonePaths.add(paths.remove(paths.size() - 1));
dp.invalidate();
}
}
});
((Button) findViewById(R.id.Redo)).setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if (undonePaths.size() > 0) {
paths.add(undonePaths.remove(undonePaths.size() - 1));
dp.invalidate();
}
}
});
((Button) findViewById(R.id.letters)).setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
startActivity(new Intent(HomeScreen.this, Letters.class));
}
});
((Button) findViewById(R.id.color)).setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
mCanvas=new Canvas();
new ColorPickerDialog(HomeScreen.this, HomeScreen.this, mPaint.getColor()).show();
}
});
dp.setDrawingCacheEnabled(true);
Bundle extras = getIntent().getExtras();
Integer userName;
if (extras != null) {
userName = extras.getInt("name");
// and get whatever type user account id is
}
dp.setBackgroundResource(R.drawable.atemplate);// set the back
// ground if you wish
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setColor(0xFFFF0000);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(20);
mEmboss = new EmbossMaskFilter(new float[] { 1, 1, 1 }, 0.4f, 6, 3.5f);
// mBlur = new BlurMaskFilter(8, BlurMaskFilter.Blur.NORMAL);
}
private Paint mPaint;
private MaskFilter mEmboss;
private MaskFilter mBlur;
public void colorChanged(int color) {
mPaint.setColor(color);
}
public class DrawingPanel extends View implements OnTouchListener {
private Canvas mCanvas;
private Path mPath;
private Paint mPaint, circlePaint, outercirclePaint;
// private ArrayList<Path> undonePaths = new ArrayList<Path>();
private float xleft, xright, xtop, xbottom;
public DrawingPanel(Context context) {
super(context);
setFocusable(true);
setFocusableInTouchMode(true);
this.setOnTouchListener(this);
circlePaint = new Paint();
mPaint = new Paint();
outercirclePaint = new Paint();
outercirclePaint.setAntiAlias(false);
circlePaint.setAntiAlias(false);
mPaint.setAntiAlias(false);
mPaint.setColor(0xFF000000);
outercirclePaint.setColor(0x44FFF000);
circlePaint.setColor(0xF57F35);
outercirclePaint.setStyle(Paint.Style.FILL_AND_STROKE);
circlePaint.setStyle(Paint.Style.FILL);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.MITER);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(10);
outercirclePaint.setStrokeWidth(10);
mCanvas = new Canvas();
mPath = new Path();
paths.add(mPath);
}
public void colorChanged(int color) {
mPaint.setColor(color);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
}
@Override
protected void onDraw(Canvas canvas) {
for (Path p : paths) {
canvas.drawPath(p, mPaint);
}
}
private float mX, mY;
private static final float TOUCH_TOLERANCE = 0;
private void touch_start(float x, float y) {
mPath.reset();
mPath.moveTo(x, y);
mX = x;
mY = y;
}
private void touch_move(float x, float y) {
float dx = Math.abs(x - mX);
float dy = Math.abs(y - mY);
if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
mPath.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);
mX = x;
mY = y;
}
}
private void touch_up() {
mPath.lineTo(mX, mY);
// commit the path to our offscreen
mCanvas.drawPath(mPath, mPaint);
// kill this so we don't double draw
mPath = new Path();
paths.add(mPath);
}
@Override
public boolean onTouch(View arg0, MotionEvent event) {
float x = event.getX();
float y = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
// if (x <= cx+circleRadius+5 && x>= cx-circleRadius-5) {
// if (y<= cy+circleRadius+5 && cy>= cy-circleRadius-5){
// paths.clear();
// return true;
// }
// }
touch_start(x, y);
invalidate();
break;
case MotionEvent.ACTION_MOVE:
touch_move(x, y);
invalidate();
break;
case MotionEvent.ACTION_UP:
touch_up();
invalidate();
break;
}
return true;
}
}
}
最佳答案
您是否正在考虑创建一个类似 android 设备中的 pattern locker 的应用程序，请尝试以这种方式实现。
@Override
public boolean onTouchEvent(MotionEvent event) {
// MotionEvent object holds X-Y values
if(event.getAction() == MotionEvent.ACTION_DOWN) {
String text = "You click at x = " + event.getX() + " and y = " + event.getY();
Toast.makeText(this, text, Toast.LENGTH_LONG).show();
}
return super.onTouchEvent(event);
}
关于android - 如何在 canvas android 中设置验证？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/22059518/