Android编程实现图片的浏览、缩放、拖动和自动居中效果
程序员文章站
2023-12-13 14:03:16
本文实例讲述了android编程实现图片的浏览、缩放、拖动和自动居中效果的方法。分享给大家供大家参考,具体如下:
touch.java
/**
* 图片浏览...
本文实例讲述了android编程实现图片的浏览、缩放、拖动和自动居中效果的方法。分享给大家供大家参考,具体如下:
touch.java
/** * 图片浏览、缩放、拖动、自动居中 */ public class touch extends activity implements ontouchlistener { matrix matrix = new matrix(); matrix savedmatrix = new matrix(); displaymetrics dm; imageview imgview; bitmap bitmap; float minscaler;// 最小缩放比例 static final float max_scale = 4f;// 最大缩放比例 static final int none = 0;// 初始状态 static final int drag = 1;// 拖动 static final int zoom = 2;// 缩放 int mode = none; pointf prev = new pointf(); pointf mid = new pointf(); float dist = 1f; @override public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.scale); imgview = (imageview) findviewbyid(r.id.imag);// 获取控件 bitmap = bitmapfactory.decoderesource(getresources(), this.getintent() .getextras().getint("img"));// 获取图片资源 imgview.setimagebitmap(bitmap);// 填充控件 imgview.setontouchlistener(this);// 设置触屏监听 dm = new displaymetrics(); getwindowmanager().getdefaultdisplay().getmetrics(dm);// 获取分辨率 minzoom(); center(); imgview.setimagematrix(matrix); } /** * 触屏监听 */ public boolean ontouch(view v, motionevent event) { switch (event.getaction() & motionevent.action_mask) { // 主点按下 case motionevent.action_down: savedmatrix.set(matrix); prev.set(event.getx(), event.gety()); mode = drag; break; // 副点按下 case motionevent.action_pointer_down: dist = spacing(event); // 如果连续两点距离大于10,则判定为多点模式 if (spacing(event) > 10f) { savedmatrix.set(matrix); midpoint(mid, event); mode = zoom; } break; case motionevent.action_up: case motionevent.action_pointer_up: mode = none; break; case motionevent.action_move: if (mode == drag) { matrix.set(savedmatrix); matrix.posttranslate(event.getx() - prev.x, event.gety() - prev.y); } else if (mode == zoom) { float newdist = spacing(event); if (newdist > 10f) { matrix.set(savedmatrix); float tscale = newdist / dist; matrix.postscale(tscale, tscale, mid.x, mid.y); } } break; } imgview.setimagematrix(matrix); checkview(); return true; } /** * 限制最大最小缩放比例,自动居中 */ private void checkview() { float p[] = new float[9]; matrix.getvalues(p); if (mode == zoom) { if (p[0] < minscaler) { matrix.setscale(minscaler, minscaler); } if (p[0] > max_scale) { matrix.set(savedmatrix); } } center(); } /** * 最小缩放比例,最大为100% */ private void minzoom() { minscaler = math.min( (float) dm.widthpixels / (float) bitmap.getwidth(), (float) dm.heightpixels / (float) bitmap.getheight()); if (minscaler < 1.0) { matrix.postscale(minscaler, minscaler); } } private void center() { center(true, true); } /** * 横向、纵向居中 */ protected void center(boolean horizontal, boolean vertical) { matrix m = new matrix(); m.set(matrix); rectf rect = new rectf(0, 0, bitmap.getwidth(), bitmap.getheight()); m.maprect(rect); float height = rect.height(); float width = rect.width(); float deltax = 0, deltay = 0; if (vertical) { // 图片小于屏幕大小,则居中显示。大于屏幕,上方留空则往上移,下方留空则往下移 int screenheight = dm.heightpixels; if (height < screenheight) { deltay = (screenheight - height) / 2 - rect.top; } else if (rect.top > 0) { deltay = -rect.top; } else if (rect.bottom < screenheight) { deltay = imgview.getheight() - rect.bottom; } } if (horizontal) { int screenwidth = dm.widthpixels; if (width < screenwidth) { deltax = (screenwidth - width) / 2 - rect.left; } else if (rect.left > 0) { deltax = -rect.left; } else if (rect.right < screenwidth) { deltax = screenwidth - rect.right; } } matrix.posttranslate(deltax, deltay); } /** * 两点的距离 */ private float spacing(motionevent event) { float x = event.getx(0) - event.getx(1); float y = event.gety(0) - event.gety(1); return floatmath.sqrt(x * x + y * y); } /** * 两点的中点 */ private void midpoint(pointf point, motionevent event) { float x = event.getx(0) + event.getx(1); float y = event.gety(0) + event.gety(1); point.set(x / 2, y / 2); } }
scale.xml
<?xml version="1.0" encoding="utf-8"?> <framelayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:layout_gravity="center" > <imageview android:id="@+id/imag" android:layout_width="fill_parent" android:layout_height="fill_parent" android:layout_gravity="center" android:scaletype="matrix" > </imageview> </framelayout>
希望本文所述对大家android程序设计有所帮助。