ppapi/api/dev/ppb_font_dev.idl

   1 /* Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2  * Use of this source code is governed by a BSD-style license that can be
   3  * found in the LICENSE file.
   4  */
   5
   6 /**
   7  * This file defines the <code>PPB_Font_Dev</code> interface.
   8  */
   9 label Chrome {
  10   M14 = 0.6
  11 };
  12
  13 [assert_size(4)]
  14 enum PP_FontFamily_Dev {
  15   /**
  16    * Uses the user's default web page font (normally either the default serif
  17    * or sans serif font).
  18    */
  19   PP_FONTFAMILY_DEFAULT = 0,
  20
  21   /**
  22    * These families will use the default web page font corresponding to the
  23    * given family.
  24    */
  25   PP_FONTFAMILY_SERIF = 1,
  26   PP_FONTFAMILY_SANSSERIF = 2,
  27   PP_FONTFAMILY_MONOSPACE = 3
  28 };
  29
  30 /**
  31  * Specifies the font weight. Normally users will only use NORMAL or BOLD.
  32  */
  33 [assert_size(4)]
  34 enum PP_FontWeight_Dev {
  35   PP_FONTWEIGHT_100 = 0,
  36   PP_FONTWEIGHT_200 = 1,
  37   PP_FONTWEIGHT_300 = 2,
  38   PP_FONTWEIGHT_400 = 3,
  39   PP_FONTWEIGHT_500 = 4,
  40   PP_FONTWEIGHT_600 = 5,
  41   PP_FONTWEIGHT_700 = 6,
  42   PP_FONTWEIGHT_800 = 7,
  43   PP_FONTWEIGHT_900 = 8,
  44   PP_FONTWEIGHT_NORMAL = PP_FONTWEIGHT_400,
  45   PP_FONTWEIGHT_BOLD = PP_FONTWEIGHT_700
  46 };
  47
  48 [assert_size(48)]
  49 struct PP_FontDescription_Dev {
  50   /**
  51    * Font face name as a string. This can also be an undefined var, in which
  52    * case the generic family will be obeyed. If the face is not available on
  53    * the system, the browser will attempt to do font fallback or pick a default
  54    * font.
  55    */
  56   PP_Var face;
  57
  58   /**
  59    * When Create()ing a font and the face is an undefined var, the family
  60    * specifies the generic font family type to use. If the face is specified,
  61    * this will be ignored.
  62    *
  63    * When Describe()ing a font, the family will be the value you passed in when
  64    * the font was created. In other words, if you specify a face name, the
  65    * family will not be updated to reflect whether the font name you requested
  66    * is serif or sans serif.
  67    */
  68   PP_FontFamily_Dev family;
  69
  70   /**
  71    * Size in pixels.
  72    *
  73    * You can specify 0 to get the default font size. The default font size
  74    * may vary depending on the requested font. The typical example is that
  75    * the user may have a different font size for the default monospace font to
  76    * give it a similar optical size to the proportionally spaced fonts.
  77    */
  78   uint32_t size;
  79
  80   /**
  81    * Normally you will use either PP_FONTWEIGHT_NORMAL or PP_FONTWEIGHT_BOLD.
  82    */
  83   PP_FontWeight_Dev weight;
  84
  85   PP_Bool italic;
  86   PP_Bool small_caps;
  87
  88   /**
  89    * Adjustment to apply to letter and word spacing, respectively. Initialize
  90    * to 0 to get normal spacing. Negative values bring letters/words closer
  91    * together, positive values separate them.
  92    */
  93   int32_t letter_spacing;
  94   int32_t word_spacing;
  95
  96   /**
  97    * Ensure that this struct is 48-bytes wide by padding the end.  In some
  98    * compilers, PP_Var is 8-byte aligned, so those compilers align this struct
  99    * on 8-byte boundaries as well and pad it to 16 bytes even without this
 100    * padding attribute.  This padding makes its size consistent across
 101    * compilers.
 102    */
 103   int32_t padding;
 104 };
 105
 106 [assert_size(20)]
 107 struct PP_FontMetrics_Dev {
 108   int32_t height;
 109   int32_t ascent;
 110   int32_t descent;
 111   int32_t line_spacing;
 112   int32_t x_height;
 113 };
 114
 115 [assert_size(24)]
 116 struct PP_TextRun_Dev {
 117   /**
 118    * This var must either be a string or a null/undefined var (which will be
 119    * treated as a 0-length string).
 120    */
 121   PP_Var text;
 122
 123   /**
 124    * Set to PP_TRUE if the text is right-to-left.
 125    *
 126    * When <code>override_direction</code> is false, the browser will perform
 127    * the Unicode Bidirectional Algorithm (http://unicode.org/reports/tr9/) on
 128    * the text. The value of the <code>rtl</code> flag specifies the
 129    * directionality of the surrounding environment. This means that Hebrew
 130    * word will always display right to left, even if <code>rtl</code> is false.
 131    *
 132    * When <code>override_direction</code> is true, no autodetection will be done
 133    * and <code>rtl</code> specifies the direction of the text.
 134    *
 135    * TODO(brettw) note that autodetection with rtl = true is currently
 136    * unimplemented.
 137    */
 138   PP_Bool rtl;
 139
 140   /**
 141    * Set to PP_TRUE to force the directionality of the text regardless of
 142    * content.
 143    *
 144    * If this flag is set, the browser will skip autodetection of the content
 145    * and will display all text in the direction specified by the
 146    * <code>rtl</code> flag.
 147    */
 148   PP_Bool override_direction;
 149 };
 150
 151 interface PPB_Font_Dev {
 152   /**
 153    * Returns a list of all available font families on the system. You can use
 154    * this list to decide whether to Create() a font.
 155    *
 156    * The return value will be a single string with null characters delimiting
 157    * the end of each font name. For example: "Arial\0Courier\0Times\0".
 158    *
 159    * Returns an undefined var on failure (this typically means you passed an
 160    * invalid instance).
 161    */
 162   PP_Var GetFontFamilies(
 163       [in] PP_Instance instance);
 164
 165   /**
 166    * Returns a font which best matches the given description. The return value
 167    * will have a non-zero ID on success, or zero on failure.
 168    */
 169   PP_Resource Create(
 170       [in] PP_Instance instance,
 171       [in] PP_FontDescription_Dev description);
 172
 173   /**
 174    * Returns PP_TRUE if the given resource is a Font. Returns PP_FALSE if the
 175    * resource is invalid or some type other than a Font.
 176    */
 177   PP_Bool IsFont(
 178       [in] PP_Resource resource);
 179
 180   /**
 181    * Loads the description and metrics of the font into the given structures.
 182    * The description will be different than the description the font was
 183    * created with since it will be filled with the real values from the font
 184    * that was actually selected.
 185    *
 186    * The PP_Var in the description should be of type Void on input. On output,
 187    * this will contain the string and will have a reference count of 1. The
 188    * plugin is responsible for calling Release on this var.
 189    *
 190    * Returns PP_TRUE on success, PP_FALSE if the font is invalid or if the Var
 191    * in the description isn't Null (to prevent leaks).
 192    */
 193   PP_Bool Describe(
 194       [in] PP_Resource font,
 195       [out] PP_FontDescription_Dev description,
 196       [out] PP_FontMetrics_Dev metrics);
 197
 198   /**
 199    * Draws the text to the image buffer.
 200    *
 201    * The given point represents the baseline of the left edge of the font,
 202    * regardless of whether it is left-to-right or right-to-left (in the case of
 203    * RTL text, this will actually represent the logical end of the text).
 204    *
 205    * The clip is optional and may be NULL. In this case, the text will be
 206    * clipped to the image.
 207    *
 208    * The image_data_is_opaque flag indicates whether subpixel antialiasing can
 209    * be performed, if it is supported. When the image below the text is
 210    * opaque, subpixel antialiasing is supported and you should set this to
 211    * PP_TRUE to pick up the user's default preferences. If your plugin is
 212    * partially transparent, then subpixel antialiasing is not possible and
 213    * grayscale antialiasing will be used instead (assuming the user has
 214    * antialiasing enabled at all).
 215    */
 216   PP_Bool DrawTextAt(
 217       [in] PP_Resource font,
 218       [in] PP_Resource image_data,
 219       [in] PP_TextRun_Dev text,
 220       [in] PP_Point position,
 221       [in] uint32_t color,
 222       [in] PP_Rect clip,
 223       [in] PP_Bool image_data_is_opaque);
 224
 225   /**
 226    * Returns the width of the given string. If the font is invalid or the var
 227    * isn't a valid string, this will return -1.
 228    *
 229    * Note that this function handles complex scripts such as Arabic, combining
 230    * accents, etc. so that adding the width of substrings won't necessarily
 231    * produce the correct width of the entire string.
 232    *
 233    * Returns -1 on failure.
 234    */
 235   int32_t MeasureText(
 236       [in] PP_Resource font,
 237       [in] PP_TextRun_Dev text);
 238
 239   /**
 240    * Returns the character at the given pixel X position from the beginning of
 241    * the string. This handles complex scripts such as Arabic, where characters
 242    * may be combined or replaced depending on the context. Returns (uint32)-1
 243    * on failure.
 244    */
 245   uint32_t CharacterOffsetForPixel(
 246       [in] PP_Resource font,
 247       [in] PP_TextRun_Dev text,
 248       [in] int32_t pixel_position);
 249
 250   /**
 251    * Returns the horizontal advance to the given character if the string was
 252    * placed at the given position. This handles complex scripts such as Arabic,
 253    * where characters may be combined or replaced depending on context. Returns
 254    * -1 on error.
 255    */
 256   int32_t PixelOffsetForCharacter(
 257       [in] PP_Resource font,
 258       [in] PP_TextRun_Dev text,
 259       [in] uint32_t char_offset);
 260 };
 261