Android的位图对齐网格 [英] Android Bitmap snap to grid

问题描述

有谁知道，如果有一个简单的方法，使拖动位图图像时对齐网格？

Does anyone know if there is a simple way to make images snap to grid when dragging a bitmap?

目前，我可以触摸一个位图，平稳地移动它在屏幕上。我希望能够让它捕捉到一个无形的网格，而你拖动。

At the moment I can touch a bitmap and move it smoothly around the screen. I want to be able to make it snap to an invisible grid whilst you are dragging.

推荐答案

这就是我在一个应用程序，我只是在一瞬间完成做。当用户拖动一些在屏幕上，我显示可见捕捉栅格，和当拖动完成对象被捕捉到该电网。要显示一个网格，我的方法是使用一个单独的自定义查看，我命名为 GridOverLayView 。它是覆盖在整个屏幕区域，很简单地画一个单元格中的的onDraw（）方法。它是可见，只有当事情被拖动。

It's what I do in an application I'm just finishing at the moment. When the user is dragging something on the screen, I display a visible snap grid, and the object is snapped to that grid when the dragging has finished. To show a grid, my approach is to use a separate custom View that I named GridOverLayView. It is overlaid over the entire screen area and it very simply draws a snap grid in its onDraw() method. It is made visible only when something is being dragged.

现在，关于实际活动中拖放的处理，我定义一个特定的常数是：

Now, concerning the actual Activity in which dragging and dropping is handled, one particular constant I've defined is:

static final int SNAP_GRID_INTERVAL = 20;

当对象被拖动周围，即当处理 event.getAction（）== MotionEvent.ACTION_MOVE 中我的 OnTouchListener ，我用下面的执行对象的位置捕捉​​到网格：

When the object is being dragged around, i.e. when processing event.getAction()==MotionEvent.ACTION_MOVE events within my OnTouchListener, I perform snapping of the object's location to grid using the following:

RelativeLayout.LayoutParams par = (RelativeLayout.LayoutParams) mThingBeingDragged.getLayoutParams();
par.topMargin = Math.round((event.getRawY() - draggedInitialY)   / SNAP_GRID_INTERVAL ) * SNAP_GRID_INTERVAL;  
par.leftMargin = Math.round((event.getRawX() - draggedInitialX)  / SNAP_GRID_INTERVAL ) * SNAP_GRID_INTERVAL;
mThingBeingDragged.setLayoutParams(par);

...其中 draggedInitialY 和 draggedInitialX 存储初始 MotionEvent.ACTION_DOWN 。

一个进一步的很好的接触，是让被拖到被抢购没有四处移动的对象，但它只是在 .ACTION_UP 当用户升降机与网格对齐他们的手指。在实践中，这种感觉好得多使用。

A further nice touch is to allow the object being dragged to be moved around without snapping, but have it snap to the grid only in the .ACTION_UP when the user lifts their finger. In practice, this feels much nicer to use.

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