📄 c++ builder 程序设计实用教程 - 8_4 视频播放程序 - 张晋 - 17xie.htm
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<P class=a1><SPAN lang=EN-US>Form1->Button3->Enabled=true;</SPAN></P>
<P class=a1><SPAN lang=EN-US>Form1->Button4->Enabled=true;</SPAN></P>
<P class=a1><SPAN lang=EN-US>Form1->Button5->Enabled=true;</SPAN></P>
<P class=a1><SPAN lang=EN-US>Form1->Button6->Enabled=true;</SPAN></P>
<P class=a1><SPAN lang=EN-US>Form1->Button7->Enabled=true;</SPAN></P>
<P class=a1><SPAN lang=EN-US>//</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">设置按钮的有效状态</SPAN></P>
<P class=a1><SPAN lang=EN-US>}</SPAN></P>
<P class=a1><SPAN
lang=EN-US>//-----------------------------------------------------------------------</SPAN></P>
<P class=MsoNormalIndent><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">程序说明：</SPAN></P>
<P class=MsoNormalIndent><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">值得注意的是，在程序的运行过程中，只有用户在对话框中选择一个有效的动画文件，单击“打开”按钮，才能成功的向系统多媒体设备传送文件的路径和将要打开的文件名，这时单击“播放”按钮才能调用</SPAN><SPAN
lang=EN-US>MediaPlayer</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">组件中的</SPAN><SPAN
lang=EN-US>Play()</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">方法来播放一个选中的音乐文件，并且设置窗体上其它组件的有效状态。</SPAN></P>
<H4><SPAN lang=EN-US>7</SPAN><SPAN
style="FONT-FAMILY: 楷体_GB2312; mso-ascii-font-family: 'Times New Roman'">．手动调节动画播放进度</SPAN></H4>
<P class=MsoNormalIndent><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">在本示例程序中，对动画播放进度的调节是通过滚动条来实现，响应滚动条动态拖动的事件是</SPAN><SPAN
lang=EN-US>ScrollBar1Scroll</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">，为此，添加如下所示的代码：</SPAN></P>
<P class=a1><SPAN lang=EN-US>void __fastcall TForm1::ScrollBar1Scroll(TObject
*Sender,</SPAN></P>
<P class=a1><SPAN lang=EN-US><SPAN
style="mso-spacerun: yes"> </SPAN>TScrollCode
ScrollCode, int &ScrollPos)</SPAN></P>
<P class=a1><SPAN lang=EN-US>{</SPAN></P>
<P class=a1><SPAN lang=EN-US>Form1->MediaPlayer1->Pause();</SPAN></P>
<P class=a1><SPAN lang=EN-US>//</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">暂停播放</SPAN></P>
<P class=a1><SPAN
lang=EN-US>Form1->MediaPlayer1->Position=Form1->ScrollBar1->Position;</SPAN></P>
<P class=a1><SPAN lang=EN-US>//</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">拖动到指定位置</SPAN></P>
<P class=a1><SPAN lang=EN-US>Form1->MediaPlayer1->Play();</SPAN></P>
<P class=a1><SPAN lang=EN-US>//</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">重新播放</SPAN></P>
<P class=a1><SPAN lang=EN-US>}</SPAN></P>
<P class=a1><SPAN
lang=EN-US>//-----------------------------------------------------------------------</SPAN></P>
<P class=MsoNormalIndent><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">程序说明：</SPAN></P>
<P class=MsoNormalIndent><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">如果在程序运行的过程中用户用鼠标左键拖动滚动条上的滑动块，就会激活组件的</SPAN><SPAN
lang=EN-US>ScrollBar1Scroll</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">事件，程序首先调用</SPAN><SPAN
lang=EN-US>MediaPlayer1</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">组件的</SPAN><SPAN
lang=EN-US>Pause()</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">方法来暂停动画的播放。</SPAN></P>
<P class=MsoNormalIndent><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">然后把当前动画播放的进度通过语句</SPAN><SPAN
lang=EN-US>Form1->MediaPlayer1->Position=Form1->ScrollBar1
->Position</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">；调节到当前滑动块的位置，最后调用</SPAN><SPAN
lang=EN-US>MediaPlayer1</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">组件的</SPAN><SPAN
lang=EN-US>Play()</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">方法重新播放动画。</SPAN></P>
<H4><SPAN lang=EN-US>8</SPAN><SPAN
style="FONT-FAMILY: 楷体_GB2312; mso-ascii-font-family: 'Times New Roman'">．运行程序</SPAN></H4>
<P class=MsoNormalIndent><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">在这里对程序其它代码的添加过程就不一一加以介绍了，如果读者有什么不清楚之处，请参看附后的源程序代码。做完以上的工作后，存储文件，按键盘上的功能键</SPAN><SPAN
lang=EN-US>F9</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">运行程序。</SPAN></P>
<P class=MsoNormalIndent><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">在程序运行的过程中，由于没有给多媒体播放设备指定程序播放文件，所以窗体上的“播放”、“暂停”和“停止”等按钮都处于无效的状态。</SPAN></P>
<P class=MsoNormalIndent><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">用鼠标的左键单击“打开”按钮，在屏幕上就会弹出一个提示用户选择动画文件的对话框。</SPAN></P>
<P class=MsoNormalIndent><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">在对话框中用键盘输入一个路径和文件名，或者用鼠标来选择一个有效的动画文件，单击“打开”按钮返回到程序运行的画面中，这时窗体上的“播放”按钮变为有效的状态。</SPAN></P>
<P class=MsoNormalIndent><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">单击“播放”按钮，在窗体的</SPAN><SPAN
lang=EN-US>Panel1</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">组件上就会播放选中的动画文件，同时滚动条会动态的显示出动画播放的进度。</SPAN></P>
<P class=MsoNormalIndent><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">程序运行结果如图</SPAN><SPAN
lang=EN-US>8-25</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">所示。</SPAN></P>
<P class=a><SPAN lang=EN-US><IMG height=286
src="C++ Builder 程序设计实用教程 - 8_4 视频播放程序 - 张晋 - 17xie.files/8941ddc5d7.jpg"
width=301 v:shapes="_x0000_i1028"></SPAN></P>
<P class=MsoCaption><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">图</SPAN><SPAN
lang=EN-US>8-25<SPAN style="mso-spacerun: yes"> </SPAN></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">程序运行结果</SPAN></P>
<P class=MsoNormalIndent><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">在窗体上的各个按钮的功能如下：</SPAN></P>
<P class=MsoNormal
style="MARGIN-LEFT: 42.5pt; TEXT-INDENT: -21.25pt; mso-list: l0 level1 lfo3; tab-stops: list 21.25pt"><SPAN
lang=EN-US
style="FONT-FAMILY: Wingdings; mso-fareast-font-family: Wingdings; mso-bidi-font-family: Wingdings"><SPAN
style="mso-list: Ignore">n<SPAN
style="FONT: 7pt 'Times New Roman'">
</SPAN></SPAN></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">“打开”按钮：打开一个对话框，从中可以选择一个有效的动画文件；</SPAN></P>
<P class=MsoNormal
style="MARGIN-LEFT: 42.5pt; TEXT-INDENT: -21.25pt; mso-list: l0 level1 lfo3; tab-stops: list 21.25pt"><SPAN
lang=EN-US
style="FONT-FAMILY: Wingdings; mso-fareast-font-family: Wingdings; mso-bidi-font-family: Wingdings"><SPAN
style="mso-list: Ignore">n<SPAN
style="FONT: 7pt 'Times New Roman'">
</SPAN></SPAN></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">“播放”按钮：如果用户打开了多媒体播放设备，那么单击这个按钮就可以播放指定的动画文件；</SPAN></P>
<P class=MsoNormal
style="MARGIN-LEFT: 42.5pt; TEXT-INDENT: -21.25pt; mso-list: l0 level1 lfo3; tab-stops: list 21.25pt"><SPAN
lang=EN-US
style="FONT-FAMILY: Wingdings; mso-fareast-font-family: Wingdings; mso-bidi-font-family: Wingdings"><SPAN
style="mso-list: Ignore">n<SPAN
style="FONT: 7pt 'Times New Roman'">
</SPAN></SPAN></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">“暂停”按钮：能够暂停动画文件的播放动作；</SPAN></P>
<P class=MsoNormal
style="MARGIN-LEFT: 42.5pt; TEXT-INDENT: -21.25pt; mso-list: l0 level1 lfo3; tab-stops: list 21.25pt"><SPAN
lang=EN-US
style="FONT-FAMILY: Wingdings; mso-fareast-font-family: Wingdings; mso-bidi-font-family: Wingdings"><SPAN
style="mso-list: Ignore">n<SPAN
style="FONT: 7pt 'Times New Roman'">
</SPAN></SPAN></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">“停止”按钮：停止播放动画文件；</SPAN></P>
<P class=MsoNormal
style="MARGIN-LEFT: 42.5pt; TEXT-INDENT: -21.25pt; mso-list: l0 level1 lfo3; tab-stops: list 21.25pt"><SPAN
lang=EN-US
style="FONT-FAMILY: Wingdings; mso-fareast-font-family: Wingdings; mso-bidi-font-family: Wingdings"><SPAN
style="mso-list: Ignore">n<SPAN
style="FONT: 7pt 'Times New Roman'">
</SPAN></SPAN></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">“快进”按钮：把当前的播放为止定位在动画文件的末尾；</SPAN></P>
<P class=MsoNormal
style="MARGIN-LEFT: 42.5pt; TEXT-INDENT: -21.25pt; mso-list: l0 level1 lfo3; tab-stops: list 21.25pt"><SPAN
lang=EN-US
style="FONT-FAMILY: Wingdings; mso-fareast-font-family: Wingdings; mso-bidi-font-family: Wingdings"><SPAN
style="mso-list: Ignore">n<SPAN
style="FONT: 7pt 'Times New Roman'">
</SPAN></SPAN></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">“快退”按钮：把把当前的播放为止定位在动画文件的开头；</SPAN></P>
<P class=MsoNormal
style="MARGIN-LEFT: 42.5pt; TEXT-INDENT: -21.25pt; mso-list: l0 level1 lfo3; tab-stops: list 21.25pt"><SPAN
lang=EN-US
style="FONT-FAMILY: Wingdings; mso-fareast-font-family: Wingdings; mso-bidi-font-family: Wingdings"><SPAN
style="mso-list: Ignore">n<SPAN
style="FONT: 7pt 'Times New Roman'">
</SPAN></SPAN></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">“步进”按钮：根据组件的属性设置来控制单步前进的桢数；</SPAN></P>
<P class=MsoNormal
style="MARGIN-LEFT: 42.5pt; TEXT-INDENT: -21.25pt; mso-list: l0 level1 lfo3; tab-stops: list 21.25pt"><SPAN
lang=EN-US
style="FONT-FAMILY: Wingdings; mso-fareast-font-family: Wingdings; mso-bidi-font-family: Wingdings"><SPAN
style="mso-list: Ignore">n<SPAN
style="FONT: 7pt 'Times New Roman'">
</SPAN></SPAN></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">“步退”按钮：根据组件的属性设置来控制单步步退的桢数。</SPAN></P>
<P class=MsoNormalIndent><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">在上面的程序运行过程中，用户可以通过“暂停”、“快进”和“停止”等按钮对动画文件的播放过程加以控制，也可以用鼠标来拖动滚动条上的滑动块来改变动画播放进度。</SPAN></P>
<P class=MsoNormalIndent><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">完整的程序源代码如下所示。</SPAN></P>
<DIV
style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 0cm; BORDER-TOP: windowtext 1pt solid; PADDING-LEFT: 0cm; PADDING-BOTTOM: 1pt; BORDER-LEFT: windowtext 1pt solid; PADDING-TOP: 1pt; BORDER-BOTTOM: windowtext 1pt solid; mso-border-alt: solid windowtext .5pt; mso-element: para-border-div">
<P class=a0
style="BORDER-RIGHT: medium none; PADDING-RIGHT: 0cm; BORDER-TOP: medium none; PADDING-LEFT: 0cm; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; PADDING-TOP: 0cm; BORDER-BOTTOM: medium none; mso-border-alt: solid windowtext .5pt; mso-padding-alt: 1.0pt 0cm 1.0pt 0cm"><SPAN
style="FONT-FAMILY: 仿宋_GB2312; mso-ascii-font-family: 'Times New Roman'">程序清单</SPAN><SPAN
lang=EN-US
style="FONT-SIZE: 9pt; mso-bidi-font-size: 10.0pt"><o:p></o:p></SPAN></P></DIV>
<P class=a1><SPAN
lang=EN-US>//-----------------------------------------------------------------------</SPAN></P>
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