Do not call setBacgroundResource() in onDraw()! You are loading and setting an image every time your view is drawn. You are actually creating a infinite "loop";
onDraw() -> setBacgroundResource() -> invalidate() -> onDraw() -> setBacgroundResource() -> etc. On Sun, Aug 30, 2009 at 11:47 AM, Nick_Zaillian<[email protected]> wrote: > > Hey all, > I am writing an app that emulates a drum machine with a step > sequencer. For those unfamiliar with step sequencers, a step > sequencer is basically a set of switches where the state of each > switch indicates whether or not a sound is to be played at a > particular point in a pattern. I've already got audio playback > working using SoundPool and can play patterns (represented as objects > containing boolean arrays mapped to audio resources) by stepping > through these patterns using a timer. What I am trying and struggling > to do at present is to write my UI. I have subclassed ToggleSwitch > and made a custom switch called SeqSwitch which, in addition to > ToggleSwitch's isChecked field, also holds an isIlluminated field. > I've written another class called SwitchController that takes an array > of these switches and has a method (which I've called runSwitches) > that, with each call, advances one switch, illuminates the current > switch, and unilluminates the previous switch (the idea is that, when > the user plays his pattern, the button representing the current step > will illuminate, letting him know the current position of playback in > the sequence). The SeqSwitches seem to render and behave fine in > response to clicks. My SwitchController.runSwitches method also works > so long as I place it in a click handler of a button in my main > Activity. When, however, I pass it into the runnable (called > PatternPlayTask) that I give to my Timer (which then calls > SwitchController.runSwitches every 300 milliseconds as it steps > through the pattern), it stops working. I have used the debugger to > make sure that the object I am passing into the runnable is the same > as the one for which the call to SwitchController.runSwitches was > working in the main activity and have found that definitely it is. > Does anybody have any idea what's going on here. Hopefully I am just > doing something totally stupid, here. I've pasted the code for my > ToggleButton subclass below, if that helps: > > package com.drummachine; > import android.widget.*; > import android.view.*; > import android.content.Context; > import com.drummachine.Instrument; > import android.util.*; > import android.content.res.TypedArray; > import android.graphics.Canvas; > import android.graphics.Paint; > import android.graphics.drawable.*; > import android.util.AttributeSet; > import android.view.View; > > > public class SeqSwitch extends ToggleButton { > > //SeqSwitch holds an isIlluminated state. > //if isIlluminated is true, onDraw will render an illuminated > //button image as the SeqSwitch's drawable (currently the same image > used for > //a ToggleButton whose isChecked == true) > public boolean isIlluminated; > > public SeqSwitch(Context context) > { > super(context); > isIlluminated = false; > > } > > //constructor called when params are taken from XML layout > public SeqSwitch(Context context, AttributeSet attributes) { > super(context, attributes); > > TypedArray a = context.obtainStyledAttributes(attributes, > R.styleable.SeqSwitch); > > isIlluminated = false; > super.setBackgroundResource > (R.drawable.seqswitchbackgroundsoneoff); > > a.recycle(); > } > > public void setIlluminated(boolean state) > { > isIlluminated = state; > this.invalidate(); > > } > > //yes, I know having illumniate() and unIlluminate() methods is > redundant > //when I have a setIlluminated(boolean) method, but I am presently > too lazy > //to rearrange code elsewhere that presently relies on these two > methods. > public void unIlluminate() > { > isIlluminated = false; > this.invalidate(); > } > > public void illuminate() > { > isIlluminated = true; > this.invalidate(); > } > > > public boolean switchIsIlluminated() > { > return isIlluminated; > } > > /** > * renders a image of a switch with an illuminated LED if either > the SeqSwitch's isChecked or > * isIllumniated == true. Otherwise it renders a drawable of a > button with an unIlluminated LED > */ > public void onDraw(Canvas canvas) > { > if(super.isChecked() == true || this.isIlluminated == true) > { > super.setBackgroundResource > (R.drawable.seqswitchbackgroundsoneonon); > } > else > { > super.setBackgroundResource > (R.drawable.seqswitchbackgroundsoneoff); > } > > } > } > > Thanks, > Nick Zaillian > > > > -- Romain Guy Android framework engineer [email protected] Note: please don't send private questions to me, as I don't have time to provide private support. All such questions should be posted on public forums, where I and others can see and answer them --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Android Developers" group. 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