Analysis of Android Multi-Touch control multitouch

<span id="Label3"></p><span style="font-family:Courier New; font-size:18px"><span style="font-family:Courier New; font-size:18px">disclaimer:</span></span><p><p><span style="font-family:Courier New; font-size:18px">Reference: http://www.jcodecraeer.com/a/anzhuokaifa/androidkaifa/2013/0226/914.html</span></p></p><p><p><span style="font-family:Courier New; font-size:18px">The following implements how the Ontouchevent () method is handled for general control touch operations through the application layer that supports multi-touch operation. At the same time, some understanding of the parameter motionevent of Ontouchevent method is Made.<br></span></p></p><p><p><span style="font-family:Courier New; font-size:18px"><br></span></p></p><span style="font-family:Courier New; font-size:18px"><span style="font-family:Courier New; font-size:18px">text:</span></span><p><p><span style="font-family:Courier New; font-size:18px">Here's a sample of two apps to learn about Multitouch in Android.</span></p></p><p><p><span style="font-family:Courier New; font-size:18px"><br></span></p></p><span style="font-family:Courier New; font-size:18px"><span style="font-family:Courier New; font-size:18px">Example One (demomultitouch-canvas):</span></span><span style="font-family:Courier New; font-size:18px"><span style="font-family:Courier New; font-size:18px">Core Technology Introduction</span></span><p><p><span style="font-family:Courier New; font-size:18px">This example uses canvas in Surfaceview to show the User's multitouch, but the core technology is still a common method: ontouchevent (motionevent event)</span></p></p><p><p><span style="font-family:Courier New; font-size:18px">Motionevent There are several ways to pay attention, but there are some common methods, if you ontouchevent use More.<br></span></p></p><p><p><span style="font-family:Courier New; font-size:18px">Event.getaction ()//get Touch Action like Action_down<br>Event.getpointercount (); Get the number of touch points, such as 2 may be two fingers simultaneously press the screen<br>Event.getpointerid (nID); For the details of each touch point, we can get the index through a loop execution Getpointerid method<br>Event.getx (nID); Gets the x position of the first, nid touch Point<br>Event.gety (nID); Gets the y position of the first-click touch<br>Event.getpressure (nID); The LCD can sense the User's finger pressure, of course, the specific level is determined by the drive and physical hardware<br>Event.getdowntime ()//press Start time<br>Event.geteventtime ()//event End Time<br>Event.geteventtime ()-event.getdowntime ()); Time spent in total press<br></span></p></p><p><p><span style="font-family:Courier New; font-size:18px"><br></span></p></p><span style="font-family:Courier New; font-size:18px"><span style="font-family:Courier New; font-size:18px">Code Show:</span></span><p><p></p></p><pre name="code" class="java">public class Mtview extends Surfaceview implements Surfaceholder.callback {private static final int max_touchpoints = 10;p Rivate static final String Start_text = "please Feel free to touch the screen to test";p rivate paint textpaint = new paint ();p rivate paint touchpaints[] = New paint[max_touchpoints];p rivate int colors[] = new int[max_touchpoints];p rivate int width, height;private Float scale = 1.0f;public mtview (context Context) {super (context); Surfaceholder holder = Getholder (); holder.addcallback (this); setfocusable (true); Make sure that our view gets the input focus Setfocusableintouchmode (true); Make sure to receive the Touch event init ();} private void init () {//initialize 10 different color brushes textpaint.setcolor (color.white); colors[0] = color.blue;colors[1] = color.red; colors[2] = color.green;colors[3] = color.yellow;colors[4] = color.cyan;colors[5] = color.magenta;colors[6] = color.dkgray;colors[7] = color.white;colors[8] = color.ltgray;colors[9] = color.gray;for (int i = 0; i < MAX_TOUCHPOINT S I++) {touchpaints[i] = new Paint (); touchpaints[i].setcolor (colors[i]);}} /** * Handle TouchScreen Event */@Overridepublic Boolean ontouchevent (motionevent Event) {//get The number of screen contacts int pointercount = Event.getpointercount (); If (pointercount > Max_touchpoints) {pointercount = max_touchpoints;} Lock the canvas and start the appropriate interface processing canvas c = Getholder (). Lockcanvas (); If (c! = Null) {c.drawcolor (color.black); if (event.getaction () = = Motionevent.action_up) {//when The hand leaves the screen, clear the screen} else {//draw a cross on each contact and coordinate information for (int i = 0; i < pointercount; i++) {int ID = Event.getpointerid (i); int x = (int) event.getx (i); int y = (int) event.gety (i);d rawcrosshairsandtext (x, y, touchpaints[i d], i, id, c);} Draw a circle for each contact (int i = 0; i < pointercount; i++) {int id = event.getpointerid (i); int x = (int) event.getx (i); int y = (int) event.gety (i);d rawcircle (x, y, touchpaints[id], c);}} After the painting, unlockgetholder (). unlockcanvasandpost (c);} Return true;} /** * Draw Cross and coordinate information * * @param x * @param y * @param paint * @param ptr * @param ID * @param c */private void Drawcrosshairsan Dtext (int x, int y, paint paint, int ptr,int id, Canvas c) {c.drawLine (0, y, width, y, paint), c.drawline (x, 0, x, height, paint), int texty = (int) ((+ + * Ptr) * scale), c.drawtext ("x" + ptr + "=" + x, ten * scale, texty, textpaint), c.drawtext ("y" + ptr + "=" + y, [x] scale, texty, textpaint); c.drawtext ("i D "+ ptr +" = "+ id, width-55 * scale, texty, textpaint);} /** * Draw Circle * * @param x * @param y * @param paint * @param c */private void drawcircle (int x, int y, paint paint, Canvas C) {c.drawcircle (x, y, * scale, paint);} /** * Enter the program when the background is painted black, then write start_text to the screen */public void surfacechanged (surfaceholder holder, int format, int width, int Height) {this.width = Width;this.height = height;if (width > Height) {this.scale = width/480f;} else {this.scale = HEIGHT/4 80f;} Textpaint.settextsize (* scale); Canvas C = Getholder (). Lockcanvas (); If (c! = Null) {c.drawcolor (color.black); float twidth = Textpaint.measuretext (start_ TEXT); c.drawtext (start_text, width/2-twidth/2, height/2, textpaint); getholder (). unlockcanvasandpost (c);}} public void Surfacecreated (surfaceholder holder) {}public void surfacedestroyed (surfaceholder holder) {}} </pre><p><p></p></p><p><p><span style="font-family:Courier New; font-size:18px"><br></span></p></p><p><p><span style="font-family:Courier New; font-size:18px">The use is also so easy:</span></p></p><p><p></p></p><pre name="code" class="java"><pre name="code" class="java">Setcontentview (new Mtview (this));</pre></pre><p><p></p></p><p><p><span style="font-family:Courier New; font-size:18px"><br></span></p></p><span style="font-family:Courier New; font-size:18px"><span style="font-family:Courier New; font-size:18px">run:</span></span><p><p><br></p></p><span style="font-family:Courier New; font-size:18px"><span style="font-family:Courier New; font-size:18px"><br></span></span><span style="font-family:Courier New; font-size:18px"><span style="font-family:Courier New; font-size:18px">Example Two (demomultitouch-imageview):</span></span><p><p><span style="font-family:Courier New; font-size:18px">Zoom in or out of an image with a multi-touch screen beforelenght to save the distance between two o'clock of the previous time afterlenght to save the distance between two o'clock of the current time</span><br></p></p><p><p></p></p><pre code_snippet_id="671091" snippet_file_name="blog_20150520_3_1421336" name="code" class="java"><pre code_snippet_id="671091" snippet_file_name="blog_20150520_3_1421336" name="code" class="java">public void Scalewithfinger (motionevent event) {float moveX = event.getx (1)-event.getx (0); float Movey = event.gety (1)- Event.gety (0); Switch (event.getaction ()) {case MotionEvent.ACTION_DOWN:beforeLenght = (float) math.sqrt ((moveX * MoveX ) + (movey * movey)); break;case motionevent.action_move://get The length between two points afterlenght = (float) math.sqrt ((moveX * moveX) + (mov EY * movey)); Float gaplenght = afterlenght-beforelenght;if (gaplenght = = 0) {break;} If the current time two o'clock distance is greater than the previous two point distance, then pass 0, otherwise 1if (gaplenght > 0) {this.setscale (scale, 0);} else {this.setscale (scale, 1);} Beforelenght = afterlenght;break;}}}</pre></pre><p><p></p></p><p><p><span style="font-family:Courier New; font-size:18px"><br></span></p></p><p><p><span style="font-family:Courier New; font-size:18px">Let the picture follow the position of the finger touch screen move beforex, y is used to save the coordinates of the previous position afterx, y is used to save the current position of the Coordinates. Their difference is the increment or decrease of the ImageView Coordinates.</span><br></p></p><pre code_snippet_id="671091" snippet_file_name="blog_20150520_4_6900122" name="code" class="java"><pre code_snippet_id="671091" snippet_file_name="blog_20150520_4_6900122" name="code" class="java">public void Movewithfinger (motionevent event) {switch (event.getaction ()) {case MotionEvent.ACTION_DOWN:beforeX = Event.getx (); Beforey = event.gety (); break;case MotionEvent.ACTION_MOVE:afterX = event.getx (); aftery = event.gety (); This.setlocation ((int) (afterx-beforex), (int) (aftery-beforey)); Beforex = Afterx;beforey = Aftery;break;case MotionEv Ent. action_up:break;}}</pre></pre><p><p><span style="font-family:Courier New; font-size:18px"><br></span></p></p><span style="font-family:Courier New; font-size:18px"><span style="font-family:Courier New; font-size:18px">used to zoom in and out ImageView because the picture is filled imageview, so there is the effect of zooming in and out of the image flag 0 is a magnified image, for 1 is to reduce the picture</span></span><p><p></p></p><pre code_snippet_id="671091" snippet_file_name="blog_20150520_5_4231696" name="code" class="java"><pre code_snippet_id="671091" snippet_file_name="blog_20150520_5_4231696" name="code" class="java">private void Setscale (float temp, int flag) {if (flag = = 0) {this.setframe (this.getleft ()-(int) (temp * this.getwidth ()) , This.gettop ()-(int) (temp * this.getheight ()), this.getright () + (int) (temp * this.getwidth ()), this.getbottom () + (int) (temp * This.getheight ()));} else {this.setframe (this.getleft () + (int) (temp * this.getwidth ()), this.gettop () + (int) (temp * this.getheight ()), This. GetRight ()-(int) (temp * this.getwidth ()), this.getbottom ()-(int) (temp * this.getheight ()));}}</pre></pre><p><p></p></p><p><p><span style="font-family:Courier New; font-size:18px"><br></span></p></p><span style="font-family:Courier New; font-size:18px"><span style="font-family:Courier New; font-size:18px">the Ontouchevent event is as Follows:</span></span><p><p></p></p><pre code_snippet_id="671091" snippet_file_name="blog_20150520_6_2709105" name="code" class="java"><pre code_snippet_id="671091" snippet_file_name="blog_20150520_6_2709105" name="code" class="java">public boolean ontouchevent (motionevent event) {if (inview (imageView, event)) {if (event.getpointercount () = = 2) {imagevi Ew.scalewithfinger (event);} else if (event.getpointercount () = = 1) {imageview.movewithfinger (event);}} Return true;}</pre></pre><span style="font-family:Courier New; font-size:18px"><span style="font-family:Courier New; font-size:18px"><br></span></span><p><p></p></p><span style="font-family:Courier New; font-size:18px"><span style="font-family:Courier New; font-size:18px">Source Download:</span></span><p><p><span style="font-family:Courier New; font-size:18px">http://download.csdn.net/detail/u013761665/8719349</span><br></p></p><p><p>Analysis of Android Multi-Touch control multitouch</p></p></span>