X toolkit intrinsics programming manual : for X11, release 4

Volume Four X Toolkit Intrinsics Programming Manual Second Edition for X11, Release 4 by. Adrian Nye and Tim O'Reilly O'Reilly & Associates, Inc. 2.3.3 The Application-defaults File ........................................................................... ............ 38 2.3.4 To Hardcode or Not to Hardcode ....................................................................... .......... 40 2.4 Connecting Widgets to Application Code .......................................................................... 41 2.4.1 Callbacks ...................................................................... .................................................. 42 2.4.2 Actions ........................................................................ ................................................... 45 2.4.2.1 The Actions Table .......................................................................... ........................... 48 2.4.2.2 Format of an Action Procedure ...................................................................... ......... 48 2.4.2.3 The Translation ..................... 49 2.4.2.4 Hardcoding Translations ................................................................... ....................... 51 2.5 More About Resources ...................................................................... ................................... 52 2.5.1 Setting and Getting Resources from the Application ................................................. 52 2.5.1.1 Setting Resources with the Varargs Interfaces ....................................................... 53 2.5.1.2 Setting Resources with the ArgList Interfaces ....................................................... 54 2.5.1.3 Getting a Resource Value .......................................................................... .............. 56 2.5.2 Core Resources ...................................................................... ........................................ 57 2.5.3 Other Inherited ...................... 59 3 More Techniques for Using Widgets .................................................................... 65 3.1 Using Composite Widgets ........................................................................ ........................... 65 3.1.1 Setting Resources for an Instance Hierarchy .............................................................. 68 3.1.2 Geometry Management in Practice ....................................................................... ....... 69 3.2 Using Conslraint ............................ 72 3.3 Using Pop Ups ............................................................................ .......................................... 75 3.4 More About Callbacks ...................................................................... ................................... 81 3.4.1 Passing Data to Callback Functions ...................................................................... ....... 81 3.4.2 Callback Lists .......................................................................... ...................................... 84 3.5 Application Resources ...................................................................... ................................... 85 3.5.1 The Application Data Structure ...................................................................... .............. 86 3.5.2 The Resource List ........................................................................... ............................... 86 3.5.3 Getting the Resources ...................................................................... ............................. 90 3.6 Command-line Options ........................................................................ ................................ 91 3.6.1 Standard Command-line ......... 91 3.6.2 Defining Your Own Command-line Options ............................................................... 93 3.7 Preventing User Customization of Widget Resources ....................................................... 97 3.7.1 Using the Varargs Interfaces ..................................................................... .................... 97 3.7.2 Using the Argument List ........ 99 3.7.2.1 Another Way to Set Arguments ...................................................................... ....... 100 3.7.2.2 Merging Argument Lists .......................................................................... .............. 102 3.8 More About Application Contexts ....................................................................... ............. 102 4 An Example Application .................................................................... ...................... 105 4.1 xbitmapl: Bitmap Editor Using a BitmapEdit Widget ................................................... 106 4.1.1 Widget Public Functions ...................................................................... ....................... 109 4.1.2 Application-defaults File ........................................................................... ................. 109 4.2 xbitmap2: Adding Scrollbars to Handle Large Bitmaps ................................................ 109 4.2.1 Overriding Translations ................................................................... ........................... 114 4.2.2 Action Arguments in the Translation Table ............................................................... 114 4.2.3 The resize_thumbs Action ......................................................................... ................. 115 4.2.4 Scrollbar Callbacks ...................................................................... ............................... 116 4.3 xbitmap3: Adding Graphics to Display the Bitmap ........................................................ 118 4.3.1 Graphics from the Application .................................................................... ............... 121 4.3.2 Writing a Bitmap File ........................................................................... ....................... 124 4.4 xbitmap4: Bitmap Editor Without a BitmapEdit Widget ............................................... 125 5 Inside a Widget ......................................................................... .................................... 137 5.1 Widget Source File Organization ................................................................... ................... 138 5.2 The Private Header File-- BitmapEdiP.h ................................................................... ...... 138 5.2.1 Parts and Records ........................................................................ ................................ 139 5.2.2 Class Part and Class Record ......................................................................... .............. 140 5.2.3 Instance Part and Instance .... 141 5.3 The Widget Implementation File-- BitmapEdit.c ........................................................... 143 5.3.1 Obligatory Include Files .......................................................................... ................... 145 5.3.2 Defining the Resource List ........................................................................... .............. 145 5.3.3 The Translation Table and Actions Table .................................................................. 148 5.3.4 Declaring Methods ........................................................................ .............................. 150 5.3.5 Initializing the Class Record ......................................................................... ............. 151 5.3.5.1 The Core Class Part ........................................................................... ..................... 151 5.3.5.2 Initializing the Core Methods ........................................................................ ........ 153 5.3.6 Description of Core ............. 155 5.3.7 Packaging the Class Record for Application Use ..................................................... 157 5.3.8 A Sample Method ......................................................................... ............................... 157 5.4 The Public Header File-- BitmapEdit.h ................................................................... ........ 160 5.5 The Process of Widget Writing ........................................................................ ................. 163 5.6 Summary of Conventions .................................................................... ............................... 164 6 Basic Widget Methods ........................................................................ ....................... 169 6.1 The X Graphics Model Inside Widgets ........................................................................ ..... 170 6.2 The initialize Method ......................................................................... ................................ 170 6.2.1 Creating GCs ............................................................................ ................................... 172 6.3 The expose ................................... 175 6.4 The set_values Method ......................................................................... ............................. 178 6.5 The resize Method ........................................................................ ...................................... 181 6.6 The query_geometry ................... 184 6.7 The destroy ................................... 187 6.8 Actions in the Widget Framework ...................................................................... .............. 188 7 Events, Translations, and Accelerators .............................................................. 193 7.1 Translation Table Syntax ......................................................................... ........................... 194 7.1.1 The Direct