Android Drawing Compass

1. Inadvertently see a compass UI, here is a simple imitation of a bit. is actually some of the changes in the canvas.

The others are:

　　

3. Simply say the idea:

1) First, draw a black disc

2) Then draw the scale on the disc (that is, some transformations on the canvas)

3) Text add

4. Directly on the code:

　　

1  Public classCompassviewextendsView {2     PrivatePaint Circlepaint, Tickpaint;3     PrivateTextpaint Textpaint;4     //Specify control width and height for adaptive5     Private floatvwidth, vheight;6     //the radius of the disc7     Private floatCompassradiu;8     //length of the scale segment9     Private floatTickheight;Ten     //font height and width One     Private floattextHeight, TextWidth; A  -      PublicCompassview (Context context) { -         Super(context); the Initpaint (context); -     } -  -      PublicCompassview (Context context, AttributeSet attrs) { +         Super(context, attrs); - Initpaint (context); +     } A  at     Private voidInitpaint (Context context) { -         //Initialize the picture disc -Circlepaint =NewPaint (Paint.anti_alias_flag |paint.dither_flag); - Circlepaint.setcolor (color.black); - Circlepaint.setstyle (Paint.Style.FILL); -  in         //initialize a scale brush -Tickpaint =NewPaint (paint.anti_alias_flag); to Tickpaint.setcolor (color.red); +Tickpaint.setstrokewidth (3); -  the         //Initialize the brush of a word *Textpaint =NewTextpaint (paint.anti_alias_flag); $ Textpaint.setcolor (color.white);Panax NotoginsengTextpaint.settextsize (20); -  the     } +  A     //self-adapting to do it here the @Override +     protected voidOnsizechanged (intWintHintOLDW,intOLDH) { -         //Gets the width and height of the control $Vwidth =W; $Vheight =h; -Compassradiu = Math.min (W, h)/2; -Tickheight = (1/12f) *Compassradiu; theTextHeight = Textpaint.descent ()-textpaint.ascent (); - Wuyi     } the  - @Override Wu     protected voidOnDraw (canvas canvas) { - Canvas.drawcolor (Color.cyan); About         //Black Disc $ canvas.drawcircle (Compassradiu, Compassradiu, Compassradiu, circlepaint); -         //draw a red scale -         intdegress; -         floatTextWidth; A  +          for(inti = 0; I < 24; i++) { the Canvas.save (); - canvas.translate (Compassradiu, Compassradiu); $             //Current canvas rotation angle thedegress = i * 15; theCanvas.rotate (15 *i); the  theCanvas.drawline (0,-compassradiu, 0,-compassradiu +Tickheight, - tickpaint); in             Switch(degress) { the              Case0: theTextWidth = Textpaint.measuretext ("45"); AboutDrawText (Canvas, "45", textWidth); the                  Break; the  the              Case45: +TextWidth = Textpaint.measuretext ("East"); -DrawText (Canvas, "East", textWidth); the                  Break;Bayi              Case90: theTextWidth = Textpaint.measuretext ("135"); theDrawText (Canvas, "135", textWidth); -                  Break; -              Case135: theTextWidth = Textpaint.measuretext ("South"); theDrawText (Canvas, "South", textWidth); the                  Break; the              Case180: -TextWidth = Textpaint.measuretext ("225"); theDrawText (Canvas, "225", textWidth); the                  Break; the              Case225:94TextWidth = Textpaint.measuretext ("West"); theDrawText (Canvas, "West", textWidth); the                  Break; the              Case270:98TextWidth = Textpaint.measuretext ("315"); AboutDrawText (Canvas, "315", textWidth); -                  Break;101              Case315:102TextWidth = Textpaint.measuretext ("North");103DrawText (Canvas, "North", textWidth);104Canvas.drawline (0, the-compassradiu + tickheight + textHeight + 10,106-TEXTWIDTH/3,-compassradiu + tickheight +TextHeight107+ 30, tickpaint);108Canvas.drawline (0,109-compassradiu + tickheight + textHeight + 10, theTEXTWIDTH/3,-compassradiu + tickheight +TextHeight111+ 30, tickpaint); the 113                  Break; the             default: the                  Break; the             }117 Canvas.restore ();118         }119  -     }121 122     Private voidDrawText (canvas canvas, String text,floattextWidth) {123 124Canvas.drawtext (text,-(TEXTWIDTH/2),-compassradiu +Tickheight the+textHeight, textpaint);126 127     } -}

After the operation is:

　　

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Android Drawing Compass