20 键盘事件
20.1 键盘事件处理函数
QWidget类中包含如下虚函数，提供对键盘事件的处理：
xxxxxxxxxx21virtual void keyPressEvent(QKeyEvent* e); // 键盘键按下事件处理函数2virtual void keyReleaseEvent(QKeyEvent* e); // 键盘键弹起事件处理函数其参数QKeyEvent描述了事件发生时的细节，如具体哪个键盘键按下、弹起，按键上的字符，等等。
20.2 案例
20.2.1 创建项目
通过QtCreator，在C:\Users\Minwei\Projects\Qt路径下，创建名为Keyboard的项目。
20.2.2 设计界面
C:\Users\Minwei\Projects\Qt\Keyboard\keyboarddialog.ui：
xxxxxxxxxx4831 2<ui version="4.0">3 <class>KeyboardDialog</class>4 <widget class="QDialog" name="KeyboardDialog">5 <property name="geometry">6 <rect>7 <x>0</x>8 <y>0</y>9 <width>400</width>10 <height>300</height>11 </rect>12 </property>13 <property name="windowTitle">14 <string>键盘</string>15 </property>16 <widget class="QLabel" name="m_block">17 <property name="geometry">18 <rect>19 <x>175</x>20 <y>125</y>21 <width>50</width>22 <height>50</height>23 </rect>24 </property>25 <property name="palette">26 <palette>27 <active>28 <colorrole role="WindowText">29 <brush brushstyle="SolidPattern">30 <color alpha="255">31 <red>0</red>32 <green>0</green>33 <blue>0</blue>34 </color>35 </brush>36 </colorrole>37 <colorrole role="Button">38 <brush brushstyle="SolidPattern">39 <color alpha="255">40 <red>0</red>41 <green>170</green>42 <blue>255</blue>43 </color>44 </brush>45 </colorrole>46 <colorrole role="Light">47 <brush brushstyle="SolidPattern">48 <color alpha="255">49 <red>127</red>50 <green>213</green>51 <blue>255</blue>52 </color>53 </brush>54 </colorrole>55 <colorrole role="Midlight">56 <brush brushstyle="SolidPattern">57 <color alpha="255">58 <red>63</red>59 <green>191</green>60 <blue>255</blue>61 </color>62 </brush>63 </colorrole>64 <colorrole role="Dark">65 <brush brushstyle="SolidPattern">66 <color alpha="255">67 <red>0</red>68 <green>85</green>69 <blue>127</blue>70 </color>71 </brush>72 </colorrole>73 <colorrole role="Mid">74 <brush brushstyle="SolidPattern">75 <color alpha="255">76 <red>0</red>77 <green>113</green>78 <blue>170</blue>79 </color>80 </brush>81 </colorrole>82 <colorrole role="Text">83 <brush brushstyle="SolidPattern">84 <color alpha="255">85 <red>0</red>86 <green>0</green>87 <blue>0</blue>88 </color>89 </brush>90 </colorrole>91 <colorrole role="BrightText">92 <brush brushstyle="SolidPattern">93 <color alpha="255">94 <red>255</red>95 <green>255</green>96 <blue>255</blue>97 </color>98 </brush>99 </colorrole>100 <colorrole role="ButtonText">101 <brush brushstyle="SolidPattern">102 <color alpha="255">103 <red>0</red>104 <green>0</green>105 <blue>0</blue>106 </color>107 </brush>108 </colorrole>109 <colorrole role="Base">110 <brush brushstyle="SolidPattern">111 <color alpha="255">112 <red>255</red>113 <green>255</green>114 <blue>255</blue>115 </color>116 </brush>117 </colorrole>118 <colorrole role="Window">119 <brush brushstyle="SolidPattern">120 <color alpha="255">121 <red>0</red>122 <green>170</green>123 <blue>255</blue>124 </color>125 </brush>126 </colorrole>127 <colorrole role="Shadow">128 <brush brushstyle="SolidPattern">129 <color alpha="255">130 <red>0</red>131 <green>0</green>132 <blue>0</blue>133 </color>134 </brush>135 </colorrole>136 <colorrole role="AlternateBase">137 <brush brushstyle="SolidPattern">138 <color alpha="255">139 <red>127</red>140 <green>212</green>141 <blue>255</blue>142 </color>143 </brush>144 </colorrole>145 <colorrole role="ToolTipBase">146 <brush brushstyle="SolidPattern">147 <color alpha="255">148 <red>255</red>149 <green>255</green>150 <blue>220</blue>151 </color>152 </brush>153 </colorrole>154 <colorrole role="ToolTipText">155 <brush brushstyle="SolidPattern">156 <color alpha="255">157 <red>0</red>158 <green>0</green>159 <blue>0</blue>160 </color>161 </brush>162 </colorrole>163 <colorrole role="PlaceholderText">164 <brush brushstyle="SolidPattern">165 <color alpha="128">166 <red>0</red>167 <green>0</green>168 <blue>0</blue>169 </color>170 </brush>171 </colorrole>172 </active>173 <inactive>174 <colorrole role="WindowText">175 <brush brushstyle="SolidPattern">176 <color alpha="255">177 <red>0</red>178 <green>0</green>179 <blue>0</blue>180 </color>181 </brush>182 </colorrole>183 <colorrole role="Button">184 <brush brushstyle="SolidPattern">185 <color alpha="255">186 <red>0</red>187 <green>170</green>188 <blue>255</blue>189 </color>190 </brush>191 </colorrole>192 <colorrole role="Light">193 <brush brushstyle="SolidPattern">194 <color alpha="255">195 <red>127</red>196 <green>213</green>197 <blue>255</blue>198 </color>199 </brush>200 </colorrole>201 <colorrole role="Midlight">202 <brush brushstyle="SolidPattern">203 <color alpha="255">204 <red>63</red>205 <green>191</green>206 <blue>255</blue>207 </color>208 </brush>209 </colorrole>210 <colorrole role="Dark">211 <brush brushstyle="SolidPattern">212 <color alpha="255">213 <red>0</red>214 <green>85</green>215 <blue>127</blue>216 </color>217 </brush>218 </colorrole>219 <colorrole role="Mid">220 <brush brushstyle="SolidPattern">221 <color alpha="255">222 <red>0</red>223 <green>113</green>224 <blue>170</blue>225 </color>226 </brush>227 </colorrole>228 <colorrole role="Text">229 <brush brushstyle="SolidPattern">230 <color alpha="255">231 <red>0</red>232 <green>0</green>233 <blue>0</blue>234 </color>235 </brush>236 </colorrole>237 <colorrole role="BrightText">238 <brush brushstyle="SolidPattern">239 <color alpha="255">240 <red>255</red>241 <green>255</green>242 <blue>255</blue>243 </color>244 </brush>245 </colorrole>246 <colorrole role="ButtonText">247 <brush brushstyle="SolidPattern">248 <color alpha="255">249 <red>0</red>250 <green>0</green>251 <blue>0</blue>252 </color>253 </brush>254 </colorrole>255 <colorrole role="Base">256 <brush brushstyle="SolidPattern">257 <color alpha="255">258 <red>255</red>259 <green>255</green>260 <blue>255</blue>261 </color>262 </brush>263 </colorrole>264 <colorrole role="Window">265 <brush brushstyle="SolidPattern">266 <color alpha="255">267 <red>0</red>268 <green>170</green>269 <blue>255</blue>270 </color>271 </brush>272 </colorrole>273 <colorrole role="Shadow">274 <brush brushstyle="SolidPattern">275 <color alpha="255">276 <red>0</red>277 <green>0</green>278 <blue>0</blue>279 </color>280 </brush>281 </colorrole>282 <colorrole role="AlternateBase">283 <brush brushstyle="SolidPattern">284 <color alpha="255">285 <red>127</red>286 <green>212</green>287 <blue>255</blue>288 </color>289 </brush>290 </colorrole>291 <colorrole role="ToolTipBase">292 <brush brushstyle="SolidPattern">293 <color alpha="255">294 <red>255</red>295 <green>255</green>296 <blue>220</blue>297 </color>298 </brush>299 </colorrole>300 <colorrole role="ToolTipText">301 <brush brushstyle="SolidPattern">302 <color alpha="255">303 <red>0</red>304 <green>0</green>305 <blue>0</blue>306 </color>307 </brush>308 </colorrole>309 <colorrole role="PlaceholderText">310 <brush brushstyle="SolidPattern">311 <color alpha="128">312 <red>0</red>313 <green>0</green>314 <blue>0</blue>315 </color>316 </brush>317 </colorrole>318 </inactive>319 <disabled>320 <colorrole role="WindowText">321 <brush brushstyle="SolidPattern">322 <color alpha="255">323 <red>0</red>324 <green>85</green>325 <blue>127</blue>326 </color>327 </brush>328 </colorrole>329 <colorrole role="Button">330 <brush brushstyle="SolidPattern">331 <color alpha="255">332 <red>0</red>333 <green>170</green>334 <blue>255</blue>335 </color>336 </brush>337 </colorrole>338 <colorrole role="Light">339 <brush brushstyle="SolidPattern">340 <color alpha="255">341 <red>127</red>342 <green>213</green>343 <blue>255</blue>344 </color>345 </brush>346 </colorrole>347 <colorrole role="Midlight">348 <brush brushstyle="SolidPattern">349 <color alpha="255">350 <red>63</red>351 <green>191</green>352 <blue>255</blue>353 </color>354 </brush>355 </colorrole>356 <colorrole role="Dark">357 <brush brushstyle="SolidPattern">358 <color alpha="255">359 <red>0</red>360 <green>85</green>361 <blue>127</blue>362 </color>363 </brush>364 </colorrole>365 <colorrole role="Mid">366 <brush brushstyle="SolidPattern">367 <color alpha="255">368 <red>0</red>369 <green>113</green>370 <blue>170</blue>371 </color>372 </brush>373 </colorrole>374 <colorrole role="Text">375 <brush brushstyle="SolidPattern">376 <color alpha="255">377 <red>0</red>378 <green>85</green>379 <blue>127</blue>380 </color>381 </brush>382 </colorrole>383 <colorrole role="BrightText">384 <brush brushstyle="SolidPattern">385 <color alpha="255">386 <red>255</red>387 <green>255</green>388 <blue>255</blue>389 </color>390 </brush>391 </colorrole>392 <colorrole role="ButtonText">393 <brush brushstyle="SolidPattern">394 <color alpha="255">395 <red>0</red>396 <green>85</green>397 <blue>127</blue>398 </color>399 </brush>400 </colorrole>401 <colorrole role="Base">402 <brush brushstyle="SolidPattern">403 <color alpha="255">404 <red>0</red>405 <green>170</green>406 <blue>255</blue>407 </color>408 </brush>409 </colorrole>410 <colorrole role="Window">411 <brush brushstyle="SolidPattern">412 <color alpha="255">413 <red>0</red>414 <green>170</green>415 <blue>255</blue>416 </color>417 </brush>418 </colorrole>419 <colorrole role="Shadow">420 <brush brushstyle="SolidPattern">421 <color alpha="255">422 <red>0</red>423 <green>0</green>424 <blue>0</blue>425 </color>426 </brush>427 </colorrole>428 <colorrole role="AlternateBase">429 <brush brushstyle="SolidPattern">430 <color alpha="255">431 <red>0</red>432 <green>170</green>433 <blue>255</blue>434 </color>435 </brush>436 </colorrole>437 <colorrole role="ToolTipBase">438 <brush brushstyle="SolidPattern">439 <color alpha="255">440 <red>255</red>441 <green>255</green>442 <blue>220</blue>443 </color>444 </brush>445 </colorrole>446 <colorrole role="ToolTipText">447 <brush brushstyle="SolidPattern">448 <color alpha="255">449 <red>0</red>450 <green>0</green>451 <blue>0</blue>452 </color>453 </brush>454 </colorrole>455 <colorrole role="PlaceholderText">456 <brush brushstyle="SolidPattern">457 <color alpha="128">458 <red>0</red>459 <green>0</green>460 <blue>0</blue>461 </color>462 </brush>463 </colorrole>464 </disabled>465 </palette>466 </property>467 <property name="autoFillBackground">468 <bool>true</bool>469 </property>470 <property name="frameShape">471 <enum>QFrame::WinPanel</enum>472 </property>473 <property name="frameShadow">474 <enum>QFrame::Raised</enum>475 </property>476 <property name="text">477 <string/>478 </property>479 </widget>480 </widget>481 <resources/>482 <connections/>483</ui>20.2.3 实现功能
C:\Users\Minwei\Projects\Qt\Keyboard\keyboarddialog.h：
xxxxxxxxxx251
4
6QT_BEGIN_NAMESPACE7namespace Ui { class KeyboardDialog; }8QT_END_NAMESPACE9
10class KeyboardDialog : public QDialog11{12 Q_OBJECT13
14public:15 KeyboardDialog(QWidget *parent = nullptr);16 ~KeyboardDialog();17
18protected:19 void keyPressEvent(QKeyEvent* e);20
21private:22 Ui::KeyboardDialog *ui;23};24
25// KEYBOARDDIALOG_HC:\Users\Minwei\Projects\Qt\Keyboard\keyboarddialog.cpp：
xxxxxxxxxx531using namespace std;3
4
6
9KeyboardDialog::KeyboardDialog(QWidget *parent)10 : QDialog(parent)11 , ui(new Ui::KeyboardDialog)12{13 ui->setupUi(this);14}15
16KeyboardDialog::~KeyboardDialog()17{18 delete ui;19}20
21void KeyboardDialog::keyPressEvent(QKeyEvent* e)22{23 QPoint blockPos = ui->m_block->pos();24 switch (e->key())25 {26 case Qt::Key_Left:27 blockPos.setX(blockPos.x() - 10);28 break;29
30 case Qt::Key_Right:31 blockPos.setX(blockPos.x() + 10);32 break;33
34 case Qt::Key_Up:35 blockPos.setY(blockPos.y() - 10);36 break;37
38 case Qt::Key_Down:39 blockPos.setY(blockPos.y() + 10);40 break;41 }42
43 QSize windowSize = size();44 QSize blockSize = ui->m_block->size();45
46 int xMin = 0, xMax = windowSize.width() - blockSize.width();47 int yMin = 0, yMax = windowSize.height() - blockSize.height();48
49 blockPos.setX(min(max(blockPos.x(), xMin), xMax));50 blockPos.setY(min(max(blockPos.y(), yMin), yMax));51
52 ui->m_block->move(blockPos);53}20.2.4 测试验证
运行效果如图所示：
