如何通过拖放将图像保持在布局内 [英] How to keep an image within layout with drag and drop
问题描述
我有以下 XML:
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/palette2"
android:id="@+id/fl" >
<ImageView
android:id="@+id/iv"
android:layout_width="10dp"
android:layout_height="10dp"
android:src="@drawable/esquare" />
</FrameLayout>
这在我的 Android 手机中提供了以下图像
Which gives the following image in my Android Phone
如何编写代码以便用户可以将图像拖动到布局中的任何位置，并且 ImageView 将始终保留在布局内?
How can I code so that user can drag the image anywhere in a layout and the ImageView will always stay within the layout?
如果 X<0 它将是 X=(X+imageview.width())
If X<0 it will be X=(X+imageview.width())
如果 Y<0 它将是 Y=(Y+imageview.height())
If Y<0 it will be Y=(Y+imageview.height())
如果 X>layout.width() 它将是 X=(X-imageview.width())
If X>layout.width() it will be X=(X-imageview.width())
如果 Y>layout.height() 它将是 Y=(Y-imageview.height())?
If Y>layout.height() it will be Y=(Y-imageview.height())?
类似的东西:
因此，如果用户拖动到视图之外，则方形图像将停留在 FrameLayout
So if the user drags outside of the view, the square image will stay in the last known location within the FrameLayout
我将布局背景转换为位图，以便我可以使用它来获取 X 和 Y 坐标并为我的应用转换为 RGB 值.
I convert the layout background to a bitmap so I can use it to get the X and Y coordinate and convert to RGB value for my app.
f = (FrameLayout) findViewById(R.id.fl);
f.setOnTouchListener(flt);
iv = (ImageView) findViewById(R.id.iv);
f.setDrawingCacheEnabled(true);
f.buildDrawingCache();
bm = f.getDrawingCache();
我有以下代码可以工作，但每隔一段时间我都会收到一个错误 NPE for x must be <= layout.width() 或 y must be <=layout.height();.有时，该应用程序允许我将布局本身拖到右侧或底部，这是不应该发生的，因为我有一个条件不允许它这样做.
I have the following code which works but every once in a while I get an error NPE for x must be <= layout.width() or y must be <= layout.height();. Sometime the app allows me to drag to the right or bottom out of the layout itself which shouldn't be happening because I have a condition for it to not allow it.
@Override
public boolean onTouch(View v, MotionEvent event) {
int x = (int)event.getX();
int y = (int)event.getY();
if (x<0) {
iv.setX(0);
iv.setY(y);
x=0;
Toast.makeText(getApplicationContext(), "x=0", 2000).show();
}
if (y<0) {
iv.setY(0);
iv.setX(x);
y=0;
Toast.makeText(getApplicationContext(), "y=0", 2000).show();
}
if (x>bm.getWidth()) {
x=bm.getWidth()-20;
iv.setX(x);
iv.setY(y);
Toast.makeText(getApplicationContext(), "x=bitmap.maxwidth(}", 2000).show();
}
if (y>bm.getHeight()) {
y=bm.getHeight()-20;
iv.setY(y);
iv.setX(x);
Toast.makeText(getApplicationContext(), "y=bitmap.maxheight(}", 2000).show();
}
if (x>0 || x<bm.getWidth() || y>0 || y<bm.getHeight()) {
int action = event.getAction();
int pixel = bm.getPixel((int)x,(int) y);
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN: {
Log.i("COORDINATES","Touch coordinates : x" + String.valueOf(x) + "y" + String.valueOf(y));
iv.setX(x);
iv.setY(y);
inRed = Color.red(pixel);
inBlue = Color.blue(pixel);
inGreen = Color.green(pixel);
Log.d("Colors","R:" +inRed +" G:" +inGreen+" B:" + inBlue);
break;
}
case MotionEvent.ACTION_MOVE:{
Log.i("COORDINATES","Touch coordinates : x" + String.valueOf(x) + "y" + String.valueOf(y));
iv.setX(x);
iv.setY(y);
inRed = Color.red(pixel);
inBlue = Color.blue(pixel);
inGreen = Color.green(pixel);
Log.d("Colors","R:" +inRed +" G:" +inGreen+" B:" + inBlue);
break;
}
}
}
return true;
}
使用下面的代码，X=0 和 Y=0 效果很好！imageview 留在里面，但是当我将 X 或 Y 拖过位图的宽度和高度时会发生问题.
With the below code, the X=0 and the Y=0 works just great! the imageview stays inside but the issue happens when I drag the X or the Y past the bitmap's width and height.
如果我向右拖动太多，这就是我的 LogCat:
This is my LogCat if I drag too much to the right:
02-09 12:34:32.791: E/AndroidRuntime(12607): FATAL EXCEPTION: main
02-09 12:34:32.791: E/AndroidRuntime(12607): java.lang.IllegalArgumentException: x must be < bitmap.width()
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.graphics.Bitmap.checkPixelAccess(Bitmap.java:1155)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.graphics.Bitmap.getPixel(Bitmap.java:1107)
02-09 12:34:32.791: E/AndroidRuntime(12607): at com.example.dragdrop.MainActivity$1.onTouch(MainActivity.java:116)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.View.dispatchTouchEvent(View.java:7241)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2168)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1903)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
02-09 12:34:32.791: E/AndroidRuntime(12607): at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1953)
02-09 12:34:32.791: E/AndroidRuntime(12607): at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1405)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.app.Activity.dispatchTouchEvent(Activity.java:2410)
02-09 12:34:32.791: E/AndroidRuntime(12607): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1901)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.View.dispatchPointerEvent(View.java:7426)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.ViewRootImpl.deliverPointerEvent(ViewRootImpl.java:3220)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:3165)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:4292)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:4271)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:4363)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:179)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.InputEventReceiver.nativeConsumeBatchedInputEvents(Native Method)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.InputEventReceiver.consumeBatchedInputEvents(InputEventReceiver.java:171)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.ViewRootImpl.doConsumeBatchedInput(ViewRootImpl.java:4342)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.ViewRootImpl$ConsumeBatchedInputRunnable.run(ViewRootImpl.java:4382)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.Choreographer.doCallbacks(Choreographer.java:562)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.Choreographer.doFrame(Choreographer.java:530)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.os.Handler.handleCallback(Handler.java:725)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.os.Handler.dispatchMessage(Handler.java:92)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.os.Looper.loop(Looper.java:137)
02-09 12:34:32.791: E/AndroidRuntime(12607): at android.app.ActivityThread.main(ActivityThread.java:5195)
02-09 12:34:32.791: E/AndroidRuntime(12607): at java.lang.reflect.Method.invokeNative(Native Method)
02-09 12:34:32.791: E/AndroidRuntime(12607): at java.lang.reflect.Method.invoke(Method.java:511)
02-09 12:34:32.791: E/AndroidRuntime(12607): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:795)
02-09 12:34:32.791: E/AndroidRuntime(12607): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:562)
02-09 12:34:32.791: E/AndroidRuntime(12607): at dalvik.system.NativeStart.main(Native Method)
推荐答案
看起来你有很多错别字导致了你的问题.
Looks like you have so e typos that cause your problem.
改变
if (x>0 || x<bm.getWidth() || y>0 || y<bm.getHeight())
进入这个
if (x>0 && x<bm.getWidth() && y>0 && y<bm.getHeight())
也许这会解决您的问题.
Maybe that'll fix your issue.
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