我正在使用最新的Android IDE。我的UI中有一个吸管图标，用户可以从应用程序抛出的位图中选择一种颜色。我在图标上设置了一个监听器，但我找不到让它等待下一次触摸的方法，从中可以计算出像素颜色。到目前为止，这是一个简单的代码：
//Open the eyedropper
dropBtn = (ImageButton) findViewById(R.id.drop_btn);
dropBtn.setOnTouchListener( new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
Toast toast = Toast.makeText(getApplicationContext(), colPickMsg, Toast.LENGTH_SHORT);
toast.show();
float x = event.getX();
float y = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
p1.x = (int) x;
p1.y = (int) y;
final int sourceColor = drawView.drawableBitmap.getPixel((int) x, (int) y);
}
}
return true;
}
});
问题是代码刚刚爆破，它报告的像素是选择吸管的图标中的一个。我需要代码等待下一次点击并报告。所有建议都将受到重视。
这是绘图视图的代码。
package com.softwareandgeneral.drawtutorial01;
import android.app.ProgressDialog;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Point;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.MotionEvent;
import android.view.View;
public class DrawingView extends View {
//drawing path
private Path drawPath;
//drawing and canvas paint
private Paint drawPaint, canvasPaint;
//initial color
private int paintColor = 0xFF660000;
//canvas
private Canvas drawCanvas;
//canvas bitmap
public Bitmap canvasBitmap, drawableBitmap;
//brush sizes
private float brushSize, lastBrushSize;
//erase flag
private boolean erase = false, paint_mode = false;
final Point p1 = new Point();
private Path path;
public DrawingView(Context context, AttributeSet attrs) {
super(context, attrs);
setupDrawing();
}
//setup drawing
private void setupDrawing() {
//prepare for drawing and setup paint stroke properties
brushSize = getResources().getInteger(R.integer.medium_size);
lastBrushSize = brushSize;
drawPath = new Path();
drawPaint = new Paint();
drawPaint.setColor(paintColor);
drawPaint.setAntiAlias(true);
drawPaint.setStrokeWidth(brushSize);
drawPaint.setStyle(Paint.Style.STROKE);
drawPaint.setStrokeJoin(Paint.Join.ROUND);
drawPaint.setStrokeCap(Paint.Cap.ROUND);
canvasPaint = new Paint(Paint.DITHER_FLAG);
}
//size assigned to view
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
canvasBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.doodle_01);
drawableBitmap = canvasBitmap.copy(Bitmap.Config.ARGB_8888, true);
drawCanvas = new Canvas(drawableBitmap);
}
//draw the view - will be called after touch event
@Override
protected void onDraw(Canvas canvas) {
canvas.drawBitmap(drawableBitmap, 0, 0, canvasPaint);
canvas.drawPath(drawPath, drawPaint);
}
//update color
public void setColor(String newColor) {
invalidate();
paintColor = Color.parseColor(newColor);
drawPaint.setColor(paintColor);
}
//set brush size
public void setBrushSize(float newSize) {
float pixelAmount = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,
newSize, getResources().getDisplayMetrics());
brushSize = pixelAmount;
drawPaint.setStrokeWidth(brushSize);
}
//get and set last brush size
public void setLastBrushSize(float lastSize) {
lastBrushSize = lastSize;
}
public float getLastBrushSize() {
return lastBrushSize;
}
//set erase true or false
public void setErase(boolean isErase) {
erase = isErase;
if (erase) drawPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
else drawPaint.setXfermode(null);
}
//start new drawing
public void startNew() {
drawCanvas.drawColor(0, PorterDuff.Mode.CLEAR);
invalidate();
}
// JRL: function to return current paint color
public int getPaintColor() {
return drawPaint.getColor();
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if (paint_mode) {
float touchX = event.getX();
float touchY = event.getY();
//respond to down, move and up events
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
drawPath.moveTo(touchX, touchY);
break;
case MotionEvent.ACTION_MOVE:
drawPath.lineTo(touchX, touchY);
break;
case MotionEvent.ACTION_UP:
drawPath.lineTo(touchX, touchY);
drawCanvas.drawPath(drawPath, drawPaint);
drawPath.reset();
break;
default:
return false;
}
//redraw
invalidate();
return true;
} else {
float x = event.getX();
float y = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
p1.x = (int) x;
p1.y = (int) y;
final int sourceColor = drawableBitmap.getPixel((int) x, (int) y);
final int targetColor = drawPaint.getColor();
new TheTask(drawableBitmap, p1, sourceColor, targetColor).execute();
invalidate();
}
return true;
}
}
}
这越来越近了。我已根据此代码片段在MainActivity.onClick（View视图）中实现了onTouch侦听器：
else if (view.getId() == R.id.drop_btn) {
//JRL: color picker button clicked
Toast toast = Toast.makeText(getApplicationContext(), colPickMsg, Toast.LENGTH_SHORT);
toast.show();
drawView.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
float x = event.getX();
float y = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
p1.x = (int) x;
p1.y = (int) y;
final int sourceColor = drawView.drawableBitmap.getPixel((int) x, (int) y);
currPaint.setBackgroundColor(sourceColor);
String hexColor = String.format("#FF%06X", (0xFFFFFF & sourceColor));
currPaint.setTag(hexColor);
drawView.setColor(hexColor);
}
}
return true;
}
});
}
这是有效的。我可以选择一种颜色，对UI的更改工作正常。什么不起作用是我被困在这个监听器 - 我想要回到的原始onTouchEventlistener。我还没有办法在Android中停止听众。
答案 0 :(得分：0)
我认为你倒退了。问题是OnTouchListener的意思是“当有什么东西触动我时，不要”当我触摸某事时，这样做。“
听众看起来不错，但是把这段代码放在OnTouchListener的颜色位图中，而不是吸管图标。
试试这个：
drawView.setOnTouchListener( new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
Toast toast = Toast.makeText(getApplicationContext(), colPickMsg, Toast.LENGTH_SHORT);
toast.show();
float x = event.getX();
float y = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
p1.x = (int) x;
p1.y = (int) y;
final int sourceColor = drawView.drawableBitmap.getPixel((int) x, (int) y);
}
}
return true;
}
});