Troubleshooting Reference

Status: 🟢 Complete reference guide
Last Updated: 2024-11-06
Movian Version: 4.8+

Overview

This reference provides quick solutions to common problems encountered when developing for Movian. Issues are organized by category with symptoms, causes, and solutions.

Quick Reference

Category	Common Issues
View Files	Syntax errors, loading failures, layout problems
Plugins	Loading failures, API errors, crashes
Properties	Binding failures, undefined values, scope errors
Layout	Positioning, sizing, visibility problems
Performance	Lag, stuttering, memory issues
Navigation	Focus problems, event handling
Media	Playback failures, codec problems
Build	Compilation errors, dependency problems

View File Issues

Syntax Error: Unexpected Token

Symptoms:

Error views/main.view:42: Unexpected token '}' after expression

Causes: - Missing semicolon - Unmatched braces - Invalid operator - Malformed expression

Solutions:

1. Check for missing semicolons:

   // ❌ Wrong
   widget(label, {
     caption: "Text"  // Missing semicolon
     color: "#FFFFFF";
   });
   
   // ✅ Correct
   widget(label, {
     caption: "Text";
     color: "#FFFFFF";
   });
   

2. Match all braces:

   // ❌ Wrong - missing closing brace
   widget(container_x, {
     widget(label, {
       caption: "Text";
     });
   // Missing }
   
   // ✅ Correct
   widget(container_x, {
     widget(label, {
       caption: "Text";
     });
   });
   

3. Use valid operators:

   // ❌ Wrong
   width: 100 @ 50;
   
   // ✅ Correct
   width: 100 + 50;
   

View File Won't Load

Symptoms: - Blank screen - Error in log: "Error loading view" - Application shows fallback content

Causes: - File path incorrect - File doesn't exist - Syntax error in file - Circular include/import

Solutions:

1. Verify file path:

   // Check path is correct
   widget(loader, {
     source: "skin://pages/home.view";  // Correct path
   });
   

2. Check file exists:

   # Verify file is in correct location
   ls -la glwskins/flat/pages/home.view
   

3. Check for syntax errors:

4. Review error log for specific line numbers
5. Use text editor with syntax checking

6. Comment out sections to isolate problem

7. Avoid circular includes:

   // ❌ Wrong - circular dependency
   // file1.view
   #include "file2.view"
   
   // file2.view
   #include "file1.view"
   
   // ✅ Correct - use #import
   // file1.view
   #import "common.view"
   
   // file2.view
   #import "common.view"  // Only loaded once
   

Macro Expansion Error

Symptoms:

Error: Macro 'ButtonWidget' not defined
Error: Argument count mismatch for macro 'Button'

Causes: - Macro not defined before use - Wrong number of arguments - Missing default values

Solutions:

1. Define macros before use:

   // ✅ Correct order
   #define Button(label) {
     widget(container_x, {
       widget(label, { caption: $label; });
     });
   }
   
   Button("Click Me");
   

2. Match argument count:

   #define Button(label, width, height) {
     widget(container_x, {
       width: $width;
       height: $height;
       widget(label, { caption: $label; });
     });
   }
   
   // ❌ Wrong - missing arguments
   Button("Click");
   
   // ✅ Correct - all arguments provided
   Button("Click", 100, 40);
   

3. Use default values:

   #define Button(label, width=100, height=40) {
     widget(container_x, {
       width: $width;
       height: $height;
       widget(label, { caption: $label; });
     });
   }
   
   // ✅ Now works with fewer arguments
   Button("Click");
   Button("Click", 200);
   Button("Click", 200, 50);
   

Unterminated String

Symptoms:

Error: Unterminated string literal

Causes: - Missing closing quote - Unescaped quote in string - Wrong quote type

Solutions:

1. Close all strings:

   // ❌ Wrong
   caption: "Hello World;
   
   // ✅ Correct
   caption: "Hello World";
   

2. Escape quotes in strings:

   // ❌ Wrong
   caption: "He said "Hello"";
   
   // ✅ Correct
   caption: "He said \"Hello\"";
   

3. Use correct quote type:

   // For plain text
   caption: "Plain text";
   
   // For rich text (HTML-like)
   caption: '<b>Bold</b> text';
   

Plugin Issues

Plugin Won't Load

Symptoms: - Plugin not visible in Movian - Error in log: "Plugin load failed" - No service registered

Causes: - Invalid plugin.json - JavaScript syntax error - Missing required fields - API version mismatch

Solutions:

1. Validate plugin.json:

   {
     "id": "myplugin",
     "version": "1.0.0",
     "title": "My Plugin",
     "synopsis": "Description",
     "author": "Your Name",
     "homepage": "https://example.com",
     "type": "javascript",
     "file": "main.js"
   }
   

2. Check JavaScript syntax:

   // Use strict mode to catch errors
   "use strict";
   
   // Check for syntax errors
   exports.init = function() {
     // Plugin code
   };
   

3. Verify API version:

   {
     "apiversion": 1,
     "type": "javascript"
   }
   

Plugin Crashes Movian

Symptoms: - Movian crashes when plugin loads - Segmentation fault - Application freeze

Causes: - Null pointer dereference - Infinite loop - Memory corruption - Invalid API call

Solutions:

1. Add error handling:

   try {
     // Potentially problematic code
     var data = JSON.parse(response);
   } catch (e) {
     console.error("Parse error:", e);
     return;
   }
   

2. Avoid infinite loops:

   // ❌ Wrong - potential infinite loop
   while (true) {
     // No break condition
   }
   
   // ✅ Correct - with break condition
   var maxIterations = 100;
   var count = 0;
   while (condition && count < maxIterations) {
     count++;
     // Loop body
   }
   

3. Validate API calls:

   // Check parameters before API calls
   if (url && typeof url === "string") {
     http.request(url);
   } else {
     console.error("Invalid URL:", url);
   }
   

HTTP Request Fails

Symptoms: - Network error - Timeout - Empty response

Causes: - Invalid URL - Network connectivity - Server error - Timeout too short

Solutions:

1. Validate URL:

   function isValidUrl(url) {
     return url && 
            typeof url === "string" && 
            (url.startsWith("http://") || url.startsWith("https://"));
   }
   
   if (isValidUrl(url)) {
     var response = http.request(url);
   } else {
     console.error("Invalid URL:", url);
   }
   

2. Increase timeout:

   var response = http.request(url, {
     timeout: 30000,  // 30 seconds
     method: "GET"
   });
   

3. Handle errors:

   try {
     var response = http.request(url);
     if (response.statuscode === 200) {
       // Success
     } else {
       console.error("HTTP error:", response.statuscode);
     }
   } catch (e) {
     console.error("Request failed:", e);
   }
   

JSON Parse Error

Symptoms:

Error: JSON parse error
SyntaxError: Unexpected token

Causes: - Invalid JSON format - Server returned HTML instead of JSON - Encoding issues

Solutions:

1. Validate JSON before parsing:

   try {
     var data = JSON.parse(response.body);
   } catch (e) {
     console.error("JSON parse error:", e);
     console.error("Response:", response.body.substring(0, 200));
     return null;
   }
   

2. Check content type:

   var contentType = response.headers["content-type"];
   if (contentType && contentType.indexOf("application/json") !== -1) {
     var data = JSON.parse(response.body);
   } else {
     console.error("Expected JSON, got:", contentType);
   }
   

3. Handle empty responses:

   if (response.body && response.body.length > 0) {
     var data = JSON.parse(response.body);
   } else {
     console.error("Empty response");
     return null;
   }
   

Property Issues

Property Not Found

Symptoms: - Widget shows no data - Log: "Property not found" - Undefined value

Causes: - Property doesn't exist - Wrong property path - Scope issue - Property not yet set

Solutions:

1. Use null coalescing:

   // Provide fallback value
   caption: $page.model.title ?? "Untitled";
   

2. Check property path:

   // ❌ Wrong path
   caption: $item.title;
   
   // ✅ Correct path in cloner
   cloner($items, container_x, {
     caption: $self.title;
   });
   

3. Verify scope:

   // In page context
   caption: $page.model.title;
   
   // In cloner context
   caption: $self.title;
   
   // In loader context
   caption: $args.title;
   

Property Not Updating

Symptoms: - Widget doesn't reflect changes - Stale data displayed - No subscription created

Causes: - Static expression (no property reference) - Subscription not created - Property path incorrect - Widget not re-evaluating

Solutions:

1. Ensure dynamic expression:

   // ❌ Static - evaluated once
   caption: "Title: " + "Fixed";
   
   // ✅ Dynamic - updates with property
   caption: "Title: " + $page.model.title;
   

2. Use debug assignment:

   // Log property changes
   caption _=_ $page.model.title;
   

3. Force re-evaluation:

   // Use property reference to trigger updates
   alpha: $page.model.updated ? 1.0 : 1.0;
   

Scope Error

Symptoms: - $self undefined - $args not available - Wrong data displayed

Causes: - Using $self outside cloner - Using $args outside loader - Incorrect scope reference

Solutions:

1. Use correct scope:

   // ❌ Wrong - $self not available
   widget(label, {
     caption: $self.title;
   });
   
   // ✅ Correct - use appropriate scope
   widget(label, {
     caption: $page.model.title;
   });
   

2. In cloner context:

   cloner($page.model.items, container_x, {
     // $self refers to current item
     widget(label, {
       caption: $self.title;
     });
   });
   

3. In loader context:

   // Parent view
   widget(loader, {
     source: "item.view";
     args: $item;
   });
   
   // item.view
   widget(label, {
     caption: $args.title;  // Access passed data
   });
   

Layout Issues

Widget Not Visible

Symptoms: - Widget exists but doesn't appear - Blank space where widget should be - No error in log

Causes: - Alpha is 0 - No size constraints - Covered by other widget - Outside parent bounds - Hidden attribute set

Solutions:

1. Check alpha:

   widget(label, {
     caption: "Text";
     alpha: 1.0;  // Ensure visible
   });
   

2. Add size constraints:

   widget(container_x, {
     height: 50;  // Specify size
     widget(label, {
       caption: "Text";
     });
   });
   

3. Check z-order:

   widget(container_z, {
     // Background first
     widget(quad, { color: "#000000"; });
     // Content on top
     widget(label, { caption: "Text"; });
   });
   

4. Verify not hidden:

   widget(label, {
     caption: "Text";
     hidden: false;  // Ensure not hidden
   });
   

Widget Wrong Size

Symptoms: - Widget too large or too small - Doesn't fit in container - Overlaps other widgets

Causes: - Missing size constraints - Conflicting constraints - Wrong weight value - Aspect ratio issues

Solutions:

1. Specify size:

   widget(container_x, {
     width: 200;
     height: 50;
   });
   

2. Use weight for flexible sizing:

   widget(container_x, {
     widget(container_y, {
       width: 200;  // Fixed width
     });
     widget(container_y, {
       weight: 1.0;  // Fills remaining space
     });
   });
   

3. Avoid conflicting constraints:

   // ❌ Wrong - conflicting
   widget(container_x, {
     width: 100;
     weight: 1.0;  // Conflicts with fixed width
   });
   
   // ✅ Correct - use one
   widget(container_x, {
     weight: 1.0;
   });
   

Widget Wrong Position

Symptoms: - Widget in wrong location - Not aligned correctly - Overlapping incorrectly

Causes: - Wrong container type - Incorrect alignment - Wrong parent - Z-order issues

Solutions:

1. Use correct container:

   // Horizontal layout
   widget(container_x, {
     widget(label, { caption: "Left"; });
     widget(label, { caption: "Right"; });
   });
   
   // Vertical layout
   widget(container_y, {
     widget(label, { caption: "Top"; });
     widget(label, { caption: "Bottom"; });
   });
   
   // Layered
   widget(container_z, {
     widget(quad, { color: "#000000"; });
     widget(label, { caption: "Overlay"; });
   });
   

2. Set alignment:

   widget(container_x, {
     alignment: center;  // Center children
     widget(label, { caption: "Centered"; });
   });
   

3. Check parent hierarchy:

   // Ensure widget is in correct parent
   widget(container_y, {
     widget(container_x, {
       // This widget is inside container_x
       widget(label, { caption: "Text"; });
     });
   });
   

Spacing Issues

Symptoms: - Widgets too close together - Too much space between widgets - Inconsistent spacing

Causes: - Missing spacing attribute - Wrong spacing value - Padding not set - Margin issues

Solutions:

1. Set spacing:

   widget(container_y, {
     spacing: 10;  // 10 pixels between children
     widget(label, { caption: "Item 1"; });
     widget(label, { caption: "Item 2"; });
   });
   

2. Use padding:

   widget(container_x, {
     padding: [10, 20, 10, 20];  // left, top, right, bottom
     widget(label, { caption: "Text"; });
   });
   

3. Add spacer widgets:

   widget(container_x, {
     widget(label, { caption: "Left"; });
     space(1);  // Flexible spacer
     widget(label, { caption: "Right"; });
   });
   

Performance Issues

Slow Rendering

Symptoms: - Lag when scrolling - Stuttering animations - Low frame rate

Causes: - Too many widgets - Complex expressions - Large images - Inefficient layout

Solutions:

1. Reduce widget count:

   // ❌ Too many widgets
   widget(container_z, {
     widget(quad, { ... });
     widget(quad, { ... });
     widget(quad, { ... });
     widget(label, { ... });
   });
   
   // ✅ Simplified
   widget(container_z, {
     widget(quad, { ... });  // Combined background
     widget(label, { ... });
   });
   

2. Simplify expressions:

   // ❌ Complex expression
   alpha: ($enabled && $visible && !$disabled) ? 
          (isNavFocused() ? 1.0 : 0.8) : 0.3;
   
   // ✅ Broken down
   $isActive = $enabled && $visible && !$disabled;
   alpha: $isActive ? (isNavFocused() ? 1.0 : 0.8) : 0.3;
   

3. Optimize images:

   # Resize large images
   convert large.png -resize 1920x1080 optimized.png
   
   # Compress images
   pngquant optimized.png
   

4. Use list widgets for scrolling:

   // ✅ Efficient for large lists
   widget(list_y, {
     cloner($items, container_x, {
       // Item template
     });
   });
   

High Memory Usage

Symptoms: - Memory usage increases over time - Application becomes slow - Eventually crashes

Causes: - Memory leaks - Too many cached items - Large images - Subscriptions not released

Solutions:

1. Limit cached items:

   // In plugin
   page.model.items = items.slice(0, 100);  // Limit items
   

2. Use smaller images:

   // Request appropriate size from API
   var imageUrl = item.image + "?size=medium";
   

3. Clean up resources:

   // In plugin cleanup
   exports.cleanup = function() {
     // Release resources
     subscriptions.forEach(function(sub) {
       sub.destroy();
     });
   };
   

Stuttering Animations

Symptoms: - Animations not smooth - Jerky transitions - Inconsistent frame rate

Causes: - Complex calculations during animation - Too many animated widgets - Inefficient iir() usage

Solutions:

1. Use appropriate iir() time constant:

   // ❌ Too fast - jerky
   alpha: iir(isNavFocused(), 1, true);
   
   // ✅ Smooth
   alpha: iir(isNavFocused(), 8, true);
   

2. Limit animated widgets:

   // Only animate focused items
   alpha: isNavFocused() ? 
          iir(1.0, 8, true) : 
          0.7;  // Static for non-focused
   

3. Avoid complex expressions in animations:

   // ❌ Complex calculation every frame
   scale: iir(isNavFocused() ? 
              ($parent.width / $self.width) : 
              1.0, 8, true);
   
   // ✅ Pre-calculate
   $targetScale = $parent.width / $self.width;
   scale: iir(isNavFocused() ? $targetScale : 1.0, 8, true);
   

Navigation Issues

Can't Focus Widget

Symptoms: - Widget not selectable - Navigation skips widget - No focus indicator

Causes: - Missing focusable attribute - Widget hidden or alpha 0 - Focus weight too low - Parent not focusable

Solutions:

1. Add focusable attribute:

   widget(container_x, {
     focusable: true;  // Make focusable
     widget(label, { caption: "Button"; });
   });
   

2. Ensure visible:

   widget(container_x, {
     focusable: true;
     alpha: 1.0;  // Ensure visible
     hidden: false;
   });
   

3. Set focus weight:

   widget(container_x, {
     focusable: true;
     focusWeight: 1.0;  // Higher priority
   });
   

Focus Indicator Not Visible

Symptoms: - Can navigate but can't see focus - No visual feedback - Hard to tell what's selected

Causes: - No focus indicator implemented - Focus indicator same color as background - Alpha too low

Solutions:

1. Add focus indicator:

   widget(container_z, {
     focusable: true;
   
     // Background with focus effect
     widget(quad, {
       color: "#444444";
       alpha: 0.6 + 0.4 * iir(isNavFocused(), 4, true);
     });
   
     widget(label, { caption: "Button"; });
   
     // Focus border
     widget(border, {
       border: 0.1em;
       color: "#FFFFFF";
       alpha: isNavFocused();
     });
   });
   

2. Use contrasting colors:

   widget(quad, {
     color: isNavFocused() ? "#FFFF00" : "#444444";
   });
   

3. Add scale effect:

   widget(container_x, {
     focusable: true;
     scale: 1.0 + 0.1 * iir(isNavFocused(), 4, true);
   });
   

Event Not Firing

Symptoms: - Button doesn't respond - onEvent handler not called - No action on activation

Causes: - Event handler syntax error - Widget not focusable - Event type wrong - Handler returns wrong value

Solutions:

1. Check event handler syntax:

   widget(container_x, {
     focusable: true;
     onEvent(activate, navOpen("test:url"));
   });
   

2. Verify widget is focusable:

   widget(container_x, {
     focusable: true;  // Required for events
     onEvent(activate, navOpen("test:url"));
   });
   

3. Use correct event type:

   // Common event types
   onEvent(activate, ...);  // Enter/Click
   onEvent(cancel, ...);    // Back/Escape
   onEvent(focus, ...);     // Gained focus
   onEvent(blur, ...);      // Lost focus
   

Media Issues

Video Won't Play

Symptoms: - Black screen - Error message - Playback fails to start

Causes: - Unsupported codec - Invalid URL - DRM protected - Network issue

Solutions:

1. Check codec support:

   // Verify video format
   console.log("Video codec:", videoInfo.codec);
   console.log("Audio codec:", audioInfo.codec);
   

2. Validate URL:

   if (videoUrl && videoUrl.startsWith("http")) {
     page.model.videoUrl = videoUrl;
   } else {
     console.error("Invalid video URL:", videoUrl);
   }
   

3. Handle DRM:

   // Check for DRM
   if (video.drm) {
     console.log("DRM protected content");
     // Handle DRM if supported
   }
   

Audio Out of Sync

Symptoms: - Audio doesn't match video - Delay in audio - Audio ahead of video

Causes: - Incorrect timestamps - Codec issues - Performance problems

Solutions:

1. Adjust audio delay:

   // In playback settings
   audioDelay: -200;  // Negative to delay audio
   

2. Check video format:

3. Verify container format (MP4, MKV, etc.)
4. Check for variable frame rate issues
5. Test with different video files

Subtitles Not Showing

Symptoms: - No subtitles displayed - Subtitle option not available - Wrong subtitles shown

Causes: - Subtitle track not detected - Wrong encoding - Subtitle format not supported

Solutions:

1. Verify subtitle track:

   // Check available subtitle tracks
   console.log("Subtitle tracks:", media.subtitleTracks);
   

2. Set subtitle track:

   // Select subtitle track
   media.currentSubtitleTrack = 0;
   

3. Check encoding:

4. Ensure UTF-8 encoding for subtitle files
5. Verify subtitle format (SRT, ASS, etc.)

Build Issues

Compilation Error

Symptoms:

error: undefined reference to 'function'
error: 'struct' has no member named 'field'

Causes: - Missing dependency - Wrong include path - API version mismatch - Platform-specific code

Solutions:

1. Install dependencies:

   # Ubuntu/Debian
   sudo apt-get install build-essential libssl-dev
   
   # macOS
   brew install openssl
   

2. Check configure options:

   ./configure --help
   ./configure --enable-feature
   

3. Clean and rebuild:

   make clean
   make
   

Linking Error

Symptoms:

error: cannot find -llibrary
undefined reference to 'symbol'

Causes: - Missing library - Wrong library path - Library version mismatch

Solutions:

1. Install missing library:

   # Find package name
   apt-cache search library-name
   
   # Install
   sudo apt-get install library-dev
   

2. Set library path:

   export LD_LIBRARY_PATH=/path/to/libs:$LD_LIBRARY_PATH
   

3. Check library version:

   pkg-config --modversion library-name
   

Platform-Specific Issues

Symptoms: - Builds on one platform but not another - Platform-specific errors - Missing platform features

Causes: - Platform-specific code - Different library versions - Missing platform dependencies

Solutions:

1. Check platform requirements:

   # Read platform-specific docs
   cat README.platform
   

2. Use platform-specific configure:

   # Linux
   ./configure.linux
   
   # macOS
   ./configure.osx
   
   # Android
   ./configure.android
   

3. Install platform dependencies:

   # Check platform requirements
   ./configure --help
   

Getting Help

Collecting Debug Information

When reporting issues, include:

1. Movian version:

   movian --version
   

2. Platform information:

   uname -a  # Linux/macOS
   

3. Error logs:

   movian --debug 2>&1 | tee movian.log
   

4. Minimal test case:

5. Create smallest example that reproduces issue
6. Include all relevant files
7. Document steps to reproduce

Community Resources

• GitHub Issues: https://github.com/andoma/movian/issues
• Forums: Check Movian community forums
• Documentation: https://github.com/andoma/movian/wiki

Reporting Bugs

When reporting bugs:

1. Search existing issues first
2. Provide clear title describing the problem
3. Include steps to reproduce
4. Attach relevant logs and files
5. Specify platform and version
6. Describe expected vs actual behavior

See Also

• Debugging View Files - Detailed debugging guide
• Syntax Reference - Complete syntax guide
• Plugin API Reference - Plugin development
• GLW Architecture - System architecture