Android-在屏幕上移动ImageView(例如拖动) [英] Android - move an ImageView on screen (Like dragging)
问题描述
我正在尝试创建一个可以像拖动一样在设备上移动ImageView的应用，例如，当我将75％的ImageView放出屏幕时，显示Toast.我一直在阅读有关MotionEvent和onTouchListener的信息，并且一直遵循问题，但这并不能说服我.
I'm trying to create an app that can move an ImageView on your device like dragging and when I put like 75% of the ImageView out of the screen show a Toast for example. I've been reading about MotionEvent and onTouchListener and I've followed this question, but it doesn't convince me.
我当前的代码是:
public class MainActivity extends AppCompatActivity implements View.OnTouchListener {
int windowwidth;
int windowheight;
private ImageView mImageView;
private ViewGroup mRrootLayout;
private int _xDelta;
private int _yDelta;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
DisplayMetrics displaymetrics = new DisplayMetrics();
this.getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
windowwidth = displaymetrics.widthPixels;
windowheight = displaymetrics.heightPixels;
mRrootLayout = (ViewGroup) findViewById(R.id.root);
mImageView = (ImageView) mRrootLayout.findViewById(R.id.im_move_zoom_rotate);
RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams(150, 150);
mImageView.setLayoutParams(layoutParams);
mImageView.setOnTouchListener(this);
}
public boolean onTouch(View view, MotionEvent event) {
final int X = (int) event.getRawX();
final int Y = (int) event.getRawY();
if(X == 0){
Toast.makeText(this, "OUT", Toast.LENGTH_SHORT).show();
}
else if (Y == 0){
Toast.makeText(this, "OUT", Toast.LENGTH_SHORT).show();
}
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
RelativeLayout.LayoutParams lParams = (RelativeLayout.LayoutParams) view.getLayoutParams();
_xDelta = X - lParams.leftMargin;
_yDelta = Y - lParams.topMargin;
break;
case MotionEvent.ACTION_UP:
break;
case MotionEvent.ACTION_POINTER_DOWN:
break;
case MotionEvent.ACTION_POINTER_UP:
break;
case MotionEvent.ACTION_MOVE:
RelativeLayout.LayoutParams layoutParams = (RelativeLayout.LayoutParams) view
.getLayoutParams();
layoutParams.leftMargin = X - _xDelta;
layoutParams.topMargin = Y - _yDelta;
layoutParams.rightMargin = -250;
layoutParams.bottomMargin = -250;
view.setLayoutParams(layoutParams);
break;
}
mRrootLayout.invalidate();
return true;
}
}
我做了那些if和else if只是想知道ImageView是否从设备中脱出，在设备的左侧和右侧似乎还可以，但是我想制作更清洁，不写，我也没有得到LayoutParams(150,150)为什么是150?另外我也不明白为什么我必须创建一个RelativeLayout.LayoutParams以及为什么必须放置
I did those if and else if just to know if the ImageView is getting out of the device, on the left and right side of the device seems like it's okay, but I'd like to make it cleaner and not hardwritted, also I don't get the LayoutParams(150,150) why 150? Also I don't get why I have to create a RelativeLayout.LayoutParams and why I have to put
layoutParams.rightMargin = -250;
layoutParams.bottomMargin = -250;
我做了if/else if是因为我想在用户要将ImageView放出设备时删除，所以我需要控制他何时尝试，目前我只获得它TOP/LEFT/没错，我还得到了设备的尺寸，只是想尝试X或Y与高度或宽度是否相同，只是显示Toast，但操作不正确.
I did the if/else if because I want to delete when the user want to put the ImageView out of the device, so I need to control when he tries to, at the moment I only got it TOP/LEFT/RIGHT not down, I also get the dimensions of my device just to try if X or Y is the same as height or widht just show the Toast but it's not doing it correctly.
现在，我的ImageView是ic_launcher，但它会更大(几乎是中间屏幕).
Now my ImageView is the ic_launcher but it will be bigger (almost middle screen).
如果您知道有其他方法可以更轻松或最简洁地完成此操作，请随时将其放在此处，我不在乎我的代码，我可以改写它，我只是想让它清晰而不是硬编码.
If you know any other way to do that easier or cleanest, feel free to put it here, I don't care about my code, I can adapt it, I just want it to be clear and not hardcoded.
推荐答案
您的例程大部分都是有效的.在下面的代码中，我注释掉了不需要的部分，并对那些需要说明的部分进行了标记.这是成品的样子:
Your routine works for the most part. In the following code, I have commented out sections that are not needed and made notations for those parts that need some explanation. Here is what the finished product looks like:
此图说明了如何计算左边距.相同类型的计算适用于上边距.
This graphic explains how the left margin is calculated. The same type of calculation applies to the top margin.
MainActivity.java
public class MainActivity extends AppCompatActivity implements View.OnTouchListener {
int windowwidth; // Actually the width of the RelativeLayout.
int windowheight; // Actually the height of the RelativeLayout.
private ImageView mImageView;
private ViewGroup mRrootLayout;
private int _xDelta;
private int _yDelta;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// We are interested when the image view leaves its parent RelativeLayout
// container and not the screen, so the following code is not needed.
// DisplayMetrics displaymetrics = new DisplayMetrics();
// this.getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
// windowwidth = displaymetrics.widthPixels;
// windowheight = displaymetrics.heightPixels;
mRrootLayout = (ViewGroup) findViewById(R.id.root);
mImageView = (ImageView) mRrootLayout.findViewById(R.id.im_move_zoom_rotate);
// These these following 2 lines that address layoutparams set the width
// and height of the ImageView to 150 pixels and, as a side effect, clear any
// params that will interfere with movement of the ImageView.
// We will rely on the XML to define the size and avoid anything that will
// interfere, so we will comment these lines out. (You can test out how a layout parameter
// can interfere by setting android:layout_centerInParent="true" in the ImageView.
// RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams(150, 150);
// RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams(150, 150);
// mImageView.setLayoutParams(layoutParams);
mImageView.setOnTouchListener(this);
// Capture the width of the RelativeLayout once it is laid out.
mRrootLayout.post(new Runnable() {
@Override
public void run() {
windowwidth = mRrootLayout.getWidth();
windowheight = mRrootLayout.getHeight();
}
});
}
// Tracks when we have reported that the image view is out of bounds so we
// don't over report.
private boolean isOutReported = false;
public boolean onTouch(View view, MotionEvent event) {
final int X = (int) event.getRawX();
final int Y = (int) event.getRawY();
// Check if the image view is out of the parent view and report it if it is.
// Only report once the image goes out and don't stack toasts.
if (isOut(view)) {
if (!isOutReported) {
isOutReported = true;
Toast.makeText(this, "OUT", Toast.LENGTH_SHORT).show();
}
} else {
isOutReported = false;
}
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
// _xDelta and _yDelta record how far inside the view we have touched. These
// values are used to compute new margins when the view is moved.
_xDelta = X - view.getLeft();
_yDelta = Y - view.getTop();
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_POINTER_DOWN:
case MotionEvent.ACTION_POINTER_UP:
// Do nothing
break;
case MotionEvent.ACTION_MOVE:
RelativeLayout.LayoutParams lp = (RelativeLayout.LayoutParams) view
.getLayoutParams();
// Image is centered to start, but we need to unhitch it to move it around.
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
lp.removeRule(RelativeLayout.CENTER_HORIZONTAL);
lp.removeRule(RelativeLayout.CENTER_VERTICAL);
} else {
lp.addRule(RelativeLayout.CENTER_HORIZONTAL, 0);
lp.addRule(RelativeLayout.CENTER_VERTICAL, 0);
}
lp.leftMargin = X - _xDelta;
lp.topMargin = Y - _yDelta;
// Negative margins here ensure that we can move off the screen to the right
// and on the bottom. Comment these lines out and you will see that
// the image will be hemmed in on the right and bottom and will actually shrink.
lp.rightMargin = view.getWidth() - lp.leftMargin - windowwidth;
lp.bottomMargin = view.getHeight() - lp.topMargin - windowheight;
view.setLayoutParams(lp);
break;
}
// invalidate is redundant if layout params are set or not needed if they are not set.
// mRrootLayout.invalidate();
return true;
}
private boolean isOut(View view) {
// Check to see if the view is out of bounds by calculating how many pixels
// of the view must be out of bounds to and checking that at least that many
// pixels are out.
float percentageOut = 0.50f;
int viewPctWidth = (int) (view.getWidth() * percentageOut);
int viewPctHeight = (int) (view.getHeight() * percentageOut);
return ((-view.getLeft() >= viewPctWidth) ||
(view.getRight() - windowwidth) > viewPctWidth ||
(-view.getTop() >= viewPctHeight) ||
(view.getBottom() - windowheight) > viewPctHeight);
}
}
activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/root"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<ImageView
android:id="@+id/im_move_zoom_rotate"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:src="@drawable/circle" />
</RelativeLayout>
这篇关于Android-在屏幕上移动ImageView(例如拖动)的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
