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1 /**************************************************************************** |
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2 ** |
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3 ** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies). |
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4 ** All rights reserved. |
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5 ** Contact: Nokia Corporation (qt-info@nokia.com) |
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16 ** GNU Lesser General Public License Usage |
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21 ** ensure the GNU Lesser General Public License version 2.1 requirements |
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24 ** In addition, as a special exception, Nokia gives you certain additional |
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35 ** |
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36 ** |
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37 ** |
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38 ** $QT_END_LICENSE$ |
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39 ** |
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40 ****************************************************************************/ |
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41 |
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42 /*! |
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43 \page qvfb.html |
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44 |
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45 \title The Virtual Framebuffer |
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46 \ingroup qt-embedded-linux |
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47 |
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48 \l{Qt for Embedded Linux} applications write directly to the |
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49 framebuffer, eliminating the need for the X Window System and |
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50 saving memory. For development and debugging purposes, a virtual |
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51 framebuffer can be used, allowing \l{Qt for Embedded Linux} |
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52 programs to be developed on a desktop machine, without switching |
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53 between consoles and X11. |
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54 |
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55 QVFb is an X11 application supplied with Qt for X11 that provides |
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56 a virtual framebuffer for Qt for Embedded Linux to use. To use it, |
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57 you need to \l{Installing Qt on X11 Platforms}{configure and |
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58 install Qt on X11 platforms} appropriately. Further requirements |
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59 can be found in the \l{Qt for Embedded Linux Requirements} |
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60 document. |
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61 |
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62 \image qt-embedded-virtualframebuffer.png |
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63 |
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64 The virtual framebuffer emulates a framebuffer using a shared |
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65 memory region and the \c qvfb tool to display the framebuffer in a |
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66 window. The \c qvfb tool also supports a feature known as a skin |
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67 which can be used to change the look and feel of the display. The |
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68 tool is located in Qt's \c tools/qvfb directory, and provides |
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69 several additional features accessible through its \gui File and |
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70 \gui View menus. |
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71 |
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72 Please note that the virtual framebuffer is a development tool |
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73 only. No security issues have been considered in the virtual |
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74 framebuffer design. It should be avoided in a production |
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75 environment; i.e. do not configure production libraries with the |
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76 \c -qvfb option. |
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77 |
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78 \tableofcontents |
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79 |
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80 \section1 Displaying the Virtual Framebuffer |
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81 |
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82 To run the \c qvfb tool displaying the virtual framebuffer, the |
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83 \l{Qt for Embedded Linux} library must be configured and compiled |
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84 with the \c -qvfb option: |
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85 |
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86 \snippet doc/src/snippets/code/doc_src_emb-qvfb.qdoc 0 |
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87 |
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88 Ensure that you have all the |
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89 \l{Qt for Embedded Linux Requirements#Additional X11 Libraries for QVFb} |
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90 {necessary libraries} needed to build the tool, then compile and run the |
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91 \c qvfb tool as a normal Qt for X11 application (i.e., do \e not compile |
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92 it as a \l{Qt for Embedded Linux} application): |
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93 |
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94 \snippet doc/src/snippets/code/doc_src_emb-qvfb.qdoc 1 |
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95 |
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96 The \c qvfb application supports the following command line |
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97 options: |
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98 |
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99 \table |
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100 \header \o Option \o Description |
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101 \row |
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102 \o \c {-width <value>} |
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103 \o The width of the virtual framebuffer (default: 240). |
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104 \row |
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105 \o \c {-height <value>} |
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106 \o The height of the virtual framebuffer (default: 320). |
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107 \row |
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108 \o \c {-depth <value>} |
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109 \o The depth of the virtual framebuffer (1, 8 or 32; default: 8). |
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110 \row |
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111 \o \c -nocursor |
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112 \o Do not display the X11 cursor in the framebuffer window. |
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113 \row |
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114 \o \c {-qwsdisplay <:id>} |
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115 \o The \l{Qt for Embedded Linux} display ID (default: 0). |
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116 \row |
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117 \o \c {-skin <name>.skin} |
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118 \o The preferred skin. Note that the skin must be located in Qt's |
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119 \c /tools/qvfb/ directory. |
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120 \row |
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121 \o \c {-zoom <factor>} |
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122 \o Scales the application view with the given factor. |
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123 |
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124 \endtable |
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125 |
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126 \section2 Skins |
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127 |
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128 A skin is a set of XML and pixmap files that tells the vitual |
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129 framebuffer what it should look like and how it should behave; a |
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130 skin can change the unrealistic default display into a display |
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131 that is similar to the target device. To access the \c qvfb tool's |
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132 menus when a skin is activated, right-click over the display. |
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133 |
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134 Note that a skin can have buttons which (when clicked) send |
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135 signals to the Qt Extended application running inside the virtual |
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136 framebuffer, just as would happen on a real device. |
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137 |
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138 \table 100% |
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139 \row |
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140 \o |
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141 \bold {Target Device Environment} |
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142 |
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143 The \c qvfb tool provides various skins by default, allowing |
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144 the user to view their application in an environment similar |
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145 to their target device. The provided skins are: |
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146 |
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147 \list |
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148 \o ClamshellPhone |
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149 \o pda |
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150 \o PDAPhone |
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151 \o Qt ExtendedPDA |
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152 \o Qt ExtendedPhone-Advanced |
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153 \o Qt ExtendedPhone-Simple |
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154 \o SmartPhone |
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155 \o SmartPhone2 |
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156 \o SmartPhoneWithButtons |
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157 \o TouchscreenPhone |
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158 \o Trolltech-Keypad |
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159 \o Trolltech-Touchscreen |
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160 \endlist |
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161 |
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162 In addition, it is possible to create custom skins. |
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163 |
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164 \o \image qt-embedded-phone.png |
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165 \o \image qt-embedded-pda.png |
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166 \endtable |
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167 |
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168 \bold {Creating Custom Skins} |
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169 |
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170 The XML and pixmap files specifying a custom skin must be located |
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171 in subdirectory of the Qt's \c /tools/qvfb directory, called \c |
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172 /customskin.skin. See the ClamshellPhone skin for an example of the |
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173 file structure: |
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174 |
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175 \snippet doc/src/snippets/code/doc_src_emb-qvfb.qdoc 2 |
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176 |
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177 The \c /ClamshellPhone.skin directory contains the following files: |
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178 |
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179 \list |
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180 \o \c ClamshellPhone.skin |
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181 \o \c ClamshellPhone1-5.png |
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182 \o \c ClamshellPhone1-5-pressed.png |
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183 \o \c ClamshellPhone1-5-closed.png |
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184 \o \c defaultbuttons.conf (only necessary for \l Qt Extended) |
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185 \endlist |
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186 |
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187 Note that the \c defaultbuttons.conf file is only necessary if the |
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188 skin is supposed to be used with \l Qt Extended (The file customizes |
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189 the launch screen applications, orders the soft keys and provides |
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190 input method hints). See the \l Qt Extended documentation for more |
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191 information. |
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192 |
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193 \table 100% |
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194 \header |
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195 \o {3,1} The ClamshellPhone Skin |
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196 \row |
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197 \o {3,1} |
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198 |
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199 \snippet doc/src/snippets/code/doc_src_emb-qvfb.qdoc 3 |
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200 |
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201 The \c ClamShellPhone.skin file quoted above, specifies three |
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202 pixmaps: One for the normal skin (\c Up), one for the activated |
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203 skin (\c Down) and one for the closed skin (\c Closed). In |
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204 addition, it is possible to specify a pixmap for the cursor (using |
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205 a \c Cursor variable). |
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206 |
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207 The file also specifies the screen size (\c Screen) and the number |
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208 of available buttons (\c Areas). Then it describes the buttons |
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209 themselves; each button is specified by its name, keycode and |
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210 coordinates. |
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211 |
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212 The coordinates are a list of at least 2 points in clockwise order |
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213 that define a shape for the button; a click inside this shape will |
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214 be treated as a click on that button. While pressed, the pixels |
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215 for the button are redrawn from the activated skin. |
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216 |
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217 \row |
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218 \row |
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219 \o |
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220 \image qt-embedded-clamshellphone-closed.png The ClamshellPhone Skin (closed) |
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221 \o |
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222 \image qt-embedded-clamshellphone.png The ClamshellPhone Skin |
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223 \o |
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224 \image qt-embedded-clamshellphone-pressed.png The ClamshellPhone Skin (pressed) |
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225 \row |
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226 \o \c ClamshellPhone1-5-closed.png |
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227 \o \c ClamshellPhone1-5.png |
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228 \o \c ClamshellPhone1-5-pressed.png |
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229 \endtable |
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230 |
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231 \section2 The File Menu |
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232 |
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233 \image qt-embedded-qvfbfilemenu.png |
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234 |
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235 The \gui File menu allows the user to configure the virtual |
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236 framebuffer display (\gui File|Configure...), save a snapshot of |
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237 the framebuffer contents (\gui {File|Save Image...}) and record |
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238 the movements in the framebuffer (\gui File|Animation...). |
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239 |
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240 When choosing the \gui File|Configure menu item, the \c qvfb tool |
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241 provides a configuration dialog allowing the user to customize the |
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242 display of the virtual framebuffer. The user can modify the size |
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243 and depth as well as the Gamma values, and also select the |
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244 preferred skin (i.e. making the virtual framebuffer simulate the |
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245 target device environment). In addition, it is possible to emulate |
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246 a touch screen and a LCD screen. |
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247 |
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248 Note that when configuring (except when changing the Gamma values |
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249 only), any applications using the virtual framebuffer will be |
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250 terminated. |
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251 |
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252 \section2 The View Menu |
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253 |
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254 \image qt-embedded-qvfbviewmenu.png |
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255 |
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256 The \gui View menu allows the user to modify the target's refresh |
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257 rate (\gui {View|Refresh Rate...}), making \c qvfb check for |
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258 updated regions more or less frequently. |
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259 |
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260 The regions of the display that have changed are updated |
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261 periodically, i.e. the virtual framebuffer is displaying discrete |
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262 snapshots of the framebuffer rather than each individual drawing |
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263 operation. For this reason drawing problems such as flickering may |
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264 not be apparent until the program is run using a real framebuffer. |
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265 If little drawing is being done, the framebuffer will not show any |
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266 updates between drawing events. If an application is displaying an |
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267 animation, the updates will be frequent, and the application and |
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268 \c qvfb will compete for processor time. |
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269 |
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270 The \gui View menu also allows the user to zoom the view of the |
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271 application (\gui {View|Zoom *}). |
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272 |
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273 \section1 Running Applications Using the Virtual Framebuffer |
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274 |
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275 Once the virtual framebuffer (the \c qvfb application) is running, |
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276 it is ready for use: Start a server application (i.e. construct a |
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277 QApplication object with the QApplication::GuiServer flag or use |
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278 the \c -qws command line parameter. See the |
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279 \l {Running Qt for Embedded Linux Applications}{running applications} |
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280 documentation for details). For example: |
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281 |
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282 \snippet doc/src/snippets/code/doc_src_emb-qvfb.qdoc 4 |
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283 |
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284 Note that as long as the virtual framebuffer is running and the |
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285 current \l{Qt for Embedded Linux} configuration supports \c qvfb, |
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286 \l{Qt for Embedded Linux} will automatically detect it and use it by |
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287 default. Alternatively, the \c -display option can be used to |
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288 specify the virtual framebuffer driver. For example: |
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289 |
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290 \snippet doc/src/snippets/code/doc_src_emb-qvfb.qdoc 5 |
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291 |
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292 \warning If \c qvfb is not running (or the current |
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293 \l{Qt for Embedded Linux} configuration doesn't support it) and the |
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294 driver is not explicitly specified, \l{Qt for Embedded Linux} will |
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295 write to the real framebuffer and the X11 display will be corrupted. |
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296 */ |