我已经实现了一个拖放系统，现在我想从源到目标绘制一条线。我怎么画这条线？我已经使用了View类的扩展，但是它没有用。这是我的代码：
public class TempDDActivity extends Activity implements OnTouchListener {
/** Called when the activity is first created. */
private View selected_item = null;
private int offset_x = 0;
private int offset_y = 0;
Boolean touchFlag=false;
boolean dropFlag=false;
LayoutParams imageParams;
ImageView imageDrop,image1,image2;
int crashX,crashY;
Drawable dropDrawable,selectDrawable;
Rect dropRect,selectRect;
int topy,leftX,rightX,bottomY;
int dropArray[];
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.main);
ViewGroup container = (ViewGroup) findViewById(R.id.container);
imageDrop=(ImageView) findViewById(R.id.ImgDrop);
image1=(ImageView) findViewById(R.id.img);
image2=(ImageView) findViewById(R.id.img2);
container.setOnTouchListener(new View.OnTouchListener()
{
public boolean onTouch(View v, MotionEvent event)
{
if(touchFlag==true)
{
System.err.println("Display If Part ::->"+touchFlag);
switch (event.getActionMasked())
{
case MotionEvent.ACTION_DOWN :
topy=imageDrop.getTop();
leftX=imageDrop.getLeft();
rightX=imageDrop.getRight();
bottomY=imageDrop.getBottom();
System.err.println("Display Top-->"+topy);
System.err.println("Display Left-->"+leftX);
System.err.println("Display Right-->"+rightX);
System.err.println("Display Bottom-->"+bottomY);
//opRect.
break;
case MotionEvent.ACTION_MOVE:
crashX=(int) event.getX();
crashY=(int) event.getY();
System.err.println("Display Here X Value-->"+crashX);
System.err.println("Display Here Y Value-->"+crashY);
int x = (int) event.getX() - offset_x;
int y = (int) event.getY() - offset_y;
//int w = getWindowManager().getDefaultDisplay().getWidth() - 100;
//int h = getWindowManager().getDefaultDisplay().getHeight() - 100;
int w = getWindowManager().getDefaultDisplay().getWidth() - 50;
int h = getWindowManager().getDefaultDisplay().getHeight() - 10;
if (x > w)
x = w;
if (y > h)
y = h;
RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(new ViewGroup.MarginLayoutParams( RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT));
lp.setMargins(x, y, 0, 0);
//Drop Image Here
if(crashX > leftX && crashX < rightX && crashY > topy && crashY < bottomY )
{
Drawable temp=selected_item.getBackground();
imageDrop.setBackgroundDrawable(temp);
imageDrop.bringToFront();
dropFlag=true;
selected_item.setVisibility(View.INVISIBLE);
}
//Drop Image Here
selected_item.setLayoutParams(lp);
break;
case MotionEvent.ACTION_UP:
//
touchFlag=false;
if(dropFlag==true)
{
dropFlag=false;
}
else
{
selected_item.setLayoutParams(imageParams);
}
break;
default:
break;
}
}else
{
System.err.println("Display Else Part ::->"+touchFlag);
}
return true;
}
});
image1.setOnTouchListener(this);
image2.setOnTouchListener(this);
}
public boolean onTouch(View v, MotionEvent event)
{
switch (event.getActionMasked())
{
case MotionEvent.ACTION_DOWN:
touchFlag=true;
offset_x = (int) event.getX();
offset_y = (int) event.getY();
selected_item = v;
imageParams=v.getLayoutParams();
break;
case MotionEvent.ACTION_UP:
selected_item=null;
touchFlag=false;
break;
default:
break;
}
return false;
}
}
答案 0 :(得分：1)
现在我想从源到目的地画一条线
首先，您需要有一个自定义视图来实际绘制线条。这将是包裹ImageViews的布局，在我看来，我认为是RelativeLayout。那个班级会是这样的：
public class DragObserverLayout extends RelativeLayout {
float startX, startY, stopX, stopY;
private Paint mPaint = new Paint();
private List<Rect> lines = new ArrayList<Rect>();
public DragObserverLayout(Context context, AttributeSet attrs) {
super(context, attrs);
mPaint.setColor(Color.GREEN);
mPaint.setStrokeWidth(2.0f);
}
@Override
protected void dispatchDraw(Canvas canvas) {
super.dispatchDraw(canvas);
final int count = lines.size();
for (int i = 0; i < count; i++) {
final Rect r = lines.get(i);
canvas.drawLine(r.left, r.top, r.right, r.bottom, mPaint);
}
}
public void addLine(Rect r) {
lines.add(r);
invalidate();
}
}
然后在您进行拖动操作的容器的OnTouchListener中，您只需执行以下操作：
final int[] location = new int[2];
final DragObserverLayout container = (DragObserverLayout ) findViewById(R.id.container);
container.setOnTouchListener(new View.OnTouchListener() {
public boolean onTouch(View v, MotionEvent event) {
if(touchFlag==true) {
switch (event.getActionMasked())
{
case MotionEvent.ACTION_DOWN :
//...
selected_item.getLocationOnScreen(location);
container.startX = location[0];
container.startY = location[1];
break;
case MotionEvent.ACTION_MOVE:
//...
selected_item.getLocationOnScreen(location);
break;
case MotionEvent.ACTION_UP:
// ...
// .. the item was dragged on the target
if (selected_item.getVisibility() != View.VISIBLE) {
Rect r = new Rect();
r.left = (int) container.startX;
r.top = (int) container.startY;
imageDrop.getLocationInWindow(location);
r.right = location[0];
r.bottom = location[1];
container.addLine(r);
}
这将从拖动的ImageView（视图的左上角）的初始位置到当前位置绘制直线，直到ImageView被“删除” ”。如果您希望通过onTouch方法对ImageViews进行一些简单计算，可以将起始线的位置偏移到指向实际触摸位置。这也适用于覆盖整个屏幕的全屏应用程序，否则您必须将getLocationOnScreen()的回报抵消以考虑状态栏。如果要在拖动操作完成后将线保留在屏幕上，则需要将其存储在容器中。