Android Picture viewer (images can be moved, scaled)

There are several ways to move and zoom a picture after a finger is clicked, which is achieved through Ontouch.

The instance code is as follows:

First, there's a ImageView in the view.

<relativelayout xmlns:android= "http://schemas.android.com/apk/res/android"    xmlns:tools= "http// Schemas.android.com/tools "    android:layout_width=" match_parent "    android:layout_height=" Match_parent "    android:paddingbottom= "@dimen/activity_vertical_margin"    android:paddingleft= "@dimen/activity_ Horizontal_margin "    android:paddingright=" @dimen/activity_horizontal_margin "    android:paddingtop=" @dimen /activity_vertical_margin "    tools:context=". Mainactivity ">    <imageview        android:id=" @+id/iv "        android:scaletype=" Matrix "        android: Layout_width= "Wrap_content"        android:layout_height= "wrap_content"        android:src= "@drawable/b"/></ Relativelayout>

Then set the ImageView for the OnTouchClick events

Iv.setontouchlistener (this);

Rewrite Ontouch

Private PointF StartPoint = new PointF ();//Get the original coordinates of the picture//set touch mode private int mode = 0, single = 1, multi = 2;//Set the click Mode, is a one touch or multipoint private matrix matrix = new Matrix ();p rivate matrix Currentmatrix = new Matrix ();p rivate float startdistance; Two o'clock starting at the distance private PointF midpoint; Center position of two points

@Overridepublic boolean OnTouch (View V, motionevent event) {switch (Event.getaction () & Motionevent.action_mask) { Case motionevent.action_down://indicates that the user is starting to touch mode = Single;currentmatrix.set (Iv.getimagematrix ()); Startpoint.set ( Event.getx (), Event.gety ()) Break;case motionevent.action_pointer_down://when there is already a contact (finger) on the screen, and another finger presses the screen mode = multi; Startdistance = Getdistance (event); Getmidpoint (event); Currentmatrix.set (Iv.getimagematrix ()); midpoint = Getmidpoint (event); Break;case motionevent.action_move://the finger moves on the screen, the event will constantly trigger if (mode = = single) {Float x = Event.getx ()-S Tartpoint.x;float y = event.gety ()-Startpoint.y;matrix.set (Currentmatrix); matrix.posttranslate (x, y);} else if (mode = = multi) {Float enddistance = getdistance (event); if (Enddistance > 10f) {float sclace = enddistance/st Artdistance;matrix.set (Currentmatrix); Matrix.postscale (Sclace, Sclace, Midpoint.x, Midpoint.y);}} Break;case motionevent.action_up://Fingers leave the screen case motionevent.action_pointer_up://when one finger leaves the screen, but there are still contacts on the screen. mode = 0;break;d Efault:break;} Iv.setimagematrix (matrix); return true;}

Here mode is used to determine what type of touch is currently used to move a picture using a single finger, and multi represents a two-finger operation for image scaling.

To move a picture:

Currentmatrix represents the current position of the picture when clicked

StartPoint is the coordinate point of the picture when clicked

Matrix.set (Currentmatrix); matrix.posttranslate (x, y);

First get the position of the picture and then pan, the distance of the shift is the distance the finger moves.

Image zoom:

As the image is scaled to be implemented with two fingers, use the motionevent.action_pointer_down

startdistance is the distance between two fingers at the start of a press.

Midpoint is the center of the two-point press.

Matrix.postscale (Sclace, Sclace, Midpoint.x, midpoint.y); These parameters represent the scale of the x-axis and y-axis scaling, and the scaling begins at that coordinate point.

Here are getmidpoint and getdistance .

Private PointF Getmidpoint (Motionevent event) {float midx= (event.getx (0) +event.getx (1))/2; float midy= (event.gety (0) + Event.gety (1))/2; return new PointF (MIDX, midy);} Private float Getdistance (motionevent event) {float dx=event.getx (1)-event.getx (0); float dy=event.gety (1)-event.gety (0); return floatmath.sqrt (Dx*dx+dy*dy);}