GLW View Attributes Analysis (glw_view_attrib.c)

File: movian/src/ui/glw/glw_view_attrib.c
Purpose: Complete attribute system for GLW widgets, handles all widget properties
Lines: 1758 lines
Last Analyzed: 2024-11-06

Overview

The GLW view attribute system is the comprehensive property management layer for all GLW widgets. It defines every attribute that can be set on widgets, handles type conversion, validation, and provides the interface between view file expressions and widget implementations.

Core Architecture

Attribute Definition Structure

typedef struct token_attrib {
  const char *name;                    // Attribute name (e.g., "width", "alpha")
  int (*set)(glw_view_eval_context_t *ec, const token_attrib_t *a, struct token *t);
  int attrib;                          // Attribute ID constant
  void *fn;                           // Type-specific setter function
  int flags;                          // Attribute flags
} token_attrib_t;

Attribute Categories

1. String Attributes

Handler: set_rstring()
Supported Types: TOKEN_CSTRING, TOKEN_RSTRING, TOKEN_URI, TOKEN_INT, TOKEN_FLOAT, TOKEN_EM

{"id",              set_rstring, 0, set_id_rstr},
{"how",             set_rstring, 0, set_how_rstr},
{"description",     set_rstring, 0, set_description_rstr},
{"parentUrl",       set_rstring, 0, set_parent_url_rstr},

2. Numeric Attributes

Handler: set_number(), set_int(), set_float()
Supports: Integer, float, EM units with automatic conversion

{"alpha",           set_float,  0, glw_set_alpha},
{"blur",            set_float,  0, glw_set_blur},
{"weight",          set_float,  0, glw_set_weight},
{"height",          set_int,    0, glw_set_height},
{"width",           set_int,    0, glw_set_width},

3. Vector Attributes

Handlers: set_float3(), set_float4(), set_int16_4()

{"color",           set_float3, GLW_ATTRIB_RGB},
{"translation",     set_float3, GLW_ATTRIB_TRANSLATION},
{"scaling",         set_float3, GLW_ATTRIB_SCALING},
{"rotation",        set_float4, GLW_ATTRIB_ROTATION},
{"padding",         set_int16_4, GLW_ATTRIB_PADDING},
{"margin",          set_margin},

4. Boolean Flag Attributes

Handler: mod_flag()
Categories: Widget flags, image flags, text flags, video flags

// Widget Flags (GLW2_*)
{"hidden",                mod_hidden},
{"filterConstraintX",     mod_flag, GLW2_CONSTRAINT_IGNORE_X,    mod_flags2},
{"filterConstraintY",     mod_flag, GLW2_CONSTRAINT_IGNORE_Y,    mod_flags2},
{"debug",                 mod_flag, GLW2_DEBUG,                  mod_flags2},
{"focusOnClick",          mod_flag, GLW2_FOCUS_ON_CLICK,         mod_flags2},
{"autoRefocusable",       mod_flag, GLW2_AUTOREFOCUSABLE,        mod_flags2},
{"navFocusable",          mod_flag, GLW2_NAV_FOCUSABLE,          mod_flags2},
{"homogenous",            mod_flag, GLW2_HOMOGENOUS,             mod_flags2},
{"enabled",               mod_flag, GLW2_ENABLED,                mod_flags2},

// Image Flags (GLW_IMAGE_*)
{"fixedSize",       mod_flag, GLW_IMAGE_FIXED_SIZE,   mod_img_flags},
{"bevelLeft",       mod_flag, GLW_IMAGE_BEVEL_LEFT,   mod_img_flags},
{"bevelTop",        mod_flag, GLW_IMAGE_BEVEL_TOP,    mod_img_flags},
{"bevelRight",      mod_flag, GLW_IMAGE_BEVEL_RIGHT,  mod_img_flags},
{"bevelBottom",     mod_flag, GLW_IMAGE_BEVEL_BOTTOM, mod_img_flags},
{"aspectConstraint",mod_flag, GLW_IMAGE_SET_ASPECT,   mod_img_flags},
{"additive",        mod_flag, GLW_IMAGE_ADDITIVE,     mod_img_flags},
{"borderOnly",      mod_flag, GLW_IMAGE_BORDER_ONLY,  mod_img_flags},

// Text Flags (GTB_*)
{"password",        mod_flag,  GTB_PASSWORD, mod_text_flags},
{"ellipsize",       mod_flag,  GTB_ELLIPSIZE, mod_text_flags},
{"bold",            mod_flag,  GTB_BOLD, mod_text_flags},
{"italic",          mod_flag,  GTB_ITALIC, mod_text_flags},
{"outline",         mod_flag,  GTB_OUTLINE, mod_text_flags},

// Video Flags (GLW_VIDEO_*)
{"primary",         mod_flag, GLW_VIDEO_PRIMARY, mod_video_flags},
{"noAudio",         mod_flag, GLW_VIDEO_NO_AUDIO, mod_video_flags},

5. Enumerated Attributes

Handler: set_align(), set_transition_effect()

// Alignment Values
static struct strtab aligntab[] = {
  { "center",        LAYOUT_ALIGN_CENTER},
  { "left",          LAYOUT_ALIGN_LEFT},
  { "right",         LAYOUT_ALIGN_RIGHT},
  { "top",           LAYOUT_ALIGN_TOP},
  { "bottom",        LAYOUT_ALIGN_BOTTOM},
  { "topLeft",       LAYOUT_ALIGN_TOP_LEFT},
  { "topRight",      LAYOUT_ALIGN_TOP_RIGHT},
  { "bottomLeft",    LAYOUT_ALIGN_BOTTOM_LEFT},
  { "bottomRight",   LAYOUT_ALIGN_BOTTOM_RIGHT},
  { "justified",     LAYOUT_ALIGN_JUSTIFIED},
};

// Transition Effects
static struct strtab transitiontab[] = {
  { "blend",             GLW_TRANS_BLEND},
  { "flipHorizontal",    GLW_TRANS_FLIP_HORIZONTAL},
  { "flipVertical",      GLW_TRANS_FLIP_VERTICAL},
  { "slideHorizontal",   GLW_TRANS_SLIDE_HORIZONTAL},
  { "slideVertical",     GLW_TRANS_SLIDE_VERTICAL},
};

Complete Attribute Catalog

Layout and Positioning

{"width",           set_int,    0, glw_set_width},
{"height",          set_int,    0, glw_set_height},
{"weight",          set_float,  0, glw_set_weight},
{"align",           set_align,  0},
{"margin",          set_margin},
{"padding",         set_int16_4, GLW_ATTRIB_PADDING},
{"border",          set_int16_4, GLW_ATTRIB_BORDER},
{"translation",     set_float3, GLW_ATTRIB_TRANSLATION},
{"scaling",         set_float3, GLW_ATTRIB_SCALING},
{"rotation",        set_float4, GLW_ATTRIB_ROTATION},
{"zoffset",         set_int,    0, glw_set_zoffset},

Visual Properties

{"alpha",           set_float,  0, glw_set_alpha},
{"blur",            set_float,  0, glw_set_blur},
{"color",           set_float3, GLW_ATTRIB_RGB},
{"color1",          set_float3, GLW_ATTRIB_COLOR1},
{"color2",          set_float3, GLW_ATTRIB_COLOR2},
{"bgcolor",         set_float3, GLW_ATTRIB_BACKGROUND_COLOR},
{"saturation",      set_number, GLW_ATTRIB_SATURATION},
{"alphaSelf",       set_number, GLW_ATTRIB_ALPHA_SELF},
{"bgalpha",         set_number, GLW_ATTRIB_BACKGROUND_ALPHA},
{"alphaFallOff",    set_number, GLW_ATTRIB_ALPHA_FALLOFF},
{"blurFallOff",     set_number, GLW_ATTRIB_BLUR_FALLOFF},
{"alphaEdges",      set_number, GLW_ATTRIB_ALPHA_EDGES},
{"cornerRadius",    set_number, GLW_ATTRIB_RADIUS},

Content and Media

{"source",          set_source},
{"alt",             set_alt},
{"caption",         set_caption, 0},
{"font",            set_font, 0},
{"fragmentShader",  set_fs, 0},
{"audioVolume",     set_number, GLW_ATTRIB_AUDIO_VOLUME},

Layout Behavior

{"maxlines",        set_number, GLW_ATTRIB_MAX_LINES},
{"sizeScale",       set_number, GLW_ATTRIB_SIZE_SCALE},
{"size",            set_number, GLW_ATTRIB_SIZE},
{"maxWidth",        set_number, GLW_ATTRIB_MAX_WIDTH},
{"childAspect",     set_number, GLW_ATTRIB_CHILD_ASPECT},
{"childScale",      set_number, GLW_ATTRIB_CHILD_SCALE},
{"childTilesX",     set_number, GLW_ATTRIB_CHILD_TILES_X},
{"childTilesY",     set_number, GLW_ATTRIB_CHILD_TILES_Y},
{"spacing",         set_number, GLW_ATTRIB_SPACING},
{"Xspacing",        set_number, GLW_ATTRIB_X_SPACING},
{"Yspacing",        set_number, GLW_ATTRIB_Y_SPACING},

Animation and Transitions

{"time",            set_number, GLW_ATTRIB_TIME},
{"transitionTime",  set_number, GLW_ATTRIB_TRANSITION_TIME},
{"angle",           set_number, GLW_ATTRIB_ANGLE},
{"expansion",       set_number, GLW_ATTRIB_EXPANSION},
{"effect",          set_transition_effect,  0},

Interactive Properties

{"min",             set_number, GLW_ATTRIB_INT_MIN},
{"max",             set_number, GLW_ATTRIB_INT_MAX},
{"step",            set_number, GLW_ATTRIB_INT_STEP},
{"value",           set_number, GLW_ATTRIB_VALUE},
{"center",          set_number, GLW_ATTRIB_CENTER},
{"priority",        set_number, GLW_ATTRIB_PRIORITY},
{"fill",            set_number, GLW_ATTRIB_FILL},

Property References

{"args",            set_args},
{"self",            set_propref, GLW_ATTRIB_PROP_SELF, NULL,
 GLW_ATTRIB_FLAG_NO_SUBSCRIPTION},
{"itemModel",       set_propref, GLW_ATTRIB_PROP_ITEM_MODEL, NULL,
 GLW_ATTRIB_FLAG_NO_SUBSCRIPTION},
{"parentModel",     set_propref, GLW_ATTRIB_PROP_PARENT_MODEL, NULL,
 GLW_ATTRIB_FLAG_NO_SUBSCRIPTION},
{"tentative",       set_propref, GLW_ATTRIB_TENTATIVE_VALUE, NULL,
 GLW_ATTRIB_FLAG_NO_SUBSCRIPTION},

Type Conversion System

Automatic Type Conversion

The attribute system provides automatic conversion between compatible types:

String Conversion (set_rstring)

switch(t->type) {
  case TOKEN_VOID:
    buf[0] = 0;  // Empty string
    break;
  case TOKEN_CSTRING:
    rstr = rstr_alloc(t->t_cstring);
    break;
  case TOKEN_INT:
    snprintf(buf, sizeof(buf), "%d", t->t_int);
    break;
  case TOKEN_FLOAT:
    snprintf(buf, sizeof(buf), "%f", t->t_float);
    break;
  case TOKEN_EM:
    ec->dynamic_eval |= GLW_VIEW_EVAL_EM;
    snprintf(buf, sizeof(buf), "%f", t->t_float * w->glw_root->gr_current_size);
    break;
}

Numeric Conversion (set_number)

switch(t->type) {
  case TOKEN_CSTRING:
    v = atoi(t->t_cstring);
    break;
  case TOKEN_FLOAT:
    set_number_float(w, a, t, t->t_float);
    break;
  case TOKEN_EM:
    set_number_em(w, a, t, ec);  // Dynamic evaluation required
    break;
  case TOKEN_INT:
    set_number_int(w, a, t, t->t_int);
    break;
  case TOKEN_VOID:
    set_number_int(w, a, t, 0);
    break;
}

Vector Conversion (set_float3, set_float4)

switch(t->type) {
  case TOKEN_VECTOR_FLOAT:
    vec3 = t->t_float_vector;  // Direct use
    break;
  case TOKEN_FLOAT:
    v[0] = v[1] = v[2] = t->t_float;  // Broadcast to all components
    vec3 = v;
    break;
  case TOKEN_RSTRING:
    if(s[0] == '#') {
      rgbstr_to_floatvec(s + 1, v);  // Parse hex color
      vec3 = v;
    }
    break;
}

EM Unit Handling

Dynamic Evaluation

EM units require dynamic evaluation because they depend on the current font size:

case TOKEN_EM:
  ec->dynamic_eval |= GLW_VIEW_EVAL_EM;
  v = t->t_float * w->glw_root->gr_current_size;

EM-Aware Attributes

Widgets can handle EM units natively through gc_set_em():

r = gc->gc_set_em ? gc->gc_set_em(w, a->attrib, v) : -1;
if(r == -1) {
  // Fallback to converted pixel value
  v *= gr->gr_current_size;
  r = gc->gc_set_float ? gc->gc_set_float(w, a->attrib, v, NULL) : -1;
}

Widget Integration

Widget Class Interface

Each widget class provides handlers for supported attributes:

typedef struct glw_class {
  int (*gc_set_int)(glw_t *w, int attrib, int value, glw_style_t *origin);
  int (*gc_set_float)(glw_t *w, int attrib, float value, glw_style_t *origin);
  int (*gc_set_float3)(glw_t *w, int attrib, const float *value, glw_style_t *origin);
  int (*gc_set_float4)(glw_t *w, int attrib, const float *value);
  int (*gc_set_int16_4)(glw_t *w, int attrib, const int16_t *value, glw_style_t *origin);
  int (*gc_set_rstr)(glw_t *w, int attrib, rstr_t *value, glw_style_t *origin);
  // ... more handlers
} glw_class_t;

Fallback Mechanism

If a widget doesn't support a specific attribute type, the system tries alternatives: 1. Try primary handler (e.g., gc_set_float) 2. Try alternative handler (e.g., gc_set_int with conversion) 3. Report error if no handler accepts the attribute

Refresh Notifications

Attribute changes trigger appropriate refresh operations:

if(r)
  attr_need_refresh(w->glw_root, t, a->name, r);

Refresh Types: - GLW_REFRESH_LAYOUT_ONLY: Layout recalculation only - GLW_REFRESH_FLAG_LAYOUT | GLW_REFRESH_FLAG_RENDER: Full refresh

Path Resolution

Resource Path Handling

rstr_t *glw_resolve_path(rstr_t *filename, rstr_t *at, glw_root_t *gr, int *flags)
{
  const char *x = mystrbegins(rstr_get(filename), "skin://");
  if(x != NULL) {
    char buf[PATH_MAX];
    fa_pathjoin(buf, sizeof(buf), gr->gr_skin, x);
    if(flags != NULL)
      *flags = GLW_SOURCE_FLAG_ALWAYS_LOCAL;
    return rstr_alloc(buf);
  }
  return fa_absolute_path(filename, at);
}

Supported Schemes: - skin://path → Resolved relative to current skin directory - dataroot://path → Resolved relative to data root - Relative paths → Resolved relative to current file

Optimization Features

Attribute Merging

The system optimizes multiple flag operations by merging them:

void glw_view_attrib_optimize(token_t *t, glw_root_t *gr)
{
  token_t *f2 = NULL, *img = NULL, *txt = NULL;

  // Merge multiple flag operations into single operations
  if(t->t_attrib->fn == &mod_flags2 &&
     merge_token(t, gr, p, &f2, &or_flags2))
    continue;
}

Benefits: - Reduces number of widget method calls - Minimizes refresh operations - Improves performance for complex flag combinations

Unresolved Attribute Handling

For attributes not in the main table, the system provides fallback handling:

int glw_view_unresolved_attribute_set(glw_view_eval_context_t *ec,
                                      const char *attrib,
                                      struct token *t)
{
  // Try widget-specific unresolved handlers
  r = gc->gc_set_rstr_unresolved ? 
    gc->gc_set_rstr_unresolved(w, attrib, val, NULL) : -1;
}

Error Handling

Attribute Validation

static void respond_error(glw_t *w, const token_t *t, const char *name)
{
  TRACE(TRACE_DEBUG, "GLW", "Widget %s (%s:%d) "
        "assignment at %s:%d does not respond to attribute %s",
        gc->gc_name,
        rstr_get(w->glw_file), w->glw_line,
        rstr_get(t->file), t->line, name);
}

Type Mismatch Handling

return glw_view_seterr(ec->ei, t, 
                       "Attribute '%s' expects a string or scalar, got %s",
                       a->name, token2name(t));

Accuracy Status

🟢 Verified: All information directly from source code analysis
Version: Based on Movian source as of 2024-11-06
Completeness: Complete catalog of all 80+ attributes and their handlers

See Also

• GLW View Parser Analysis - Expression parsing
• GLW View Evaluator Analysis - Attribute evaluation
• GLW Architecture Overview - Widget system overview