第二人生的源码分析(八十八)LLButton类显示按钮的名称

前面介绍按钮可以显示在窗口里，以及这个类的声明，现在来仔细地分析一下它是怎么样实现名称显示的。

在构造函数里先保存传送入来的名称，如下：

#001     mUnselectedLabel = unselected_label;

#002     mSelectedLabel = selected_label;

#003 

 

从类声明里可以看到 mSelectedLabel和mUnselectedLabel都是声明为类LLUIString的实例，由于类LLUIString只支持LLString构造函数的名称，因此它不能显示UNICODE的字符串。

 

显示按钮的函数如下：

#001 void LLButton::draw()

#002 {

 

查看这个按键是否可以显示。

#003     if( getVisible() )

#004     {

 

设置动态效果。

#005         BOOL flash = FALSE;

#006         if( mFlashing )

#007         {

#008              F32 elapsed = mFlashingTimer.getElapsedTimeF32();

#009             S32 flash_count = S32(elapsed * LLUI::sConfigGroup->getF32("ButtonFlashRate") * 2.f);

#010             // flash on or off?

#011             flash = (flash_count % 2 == 0) || flash_count > (F32)LLUI::sConfigGroup->getS32("ButtonFlashCount");

#012         }

#013 

 

是否有输入焦点。

#014         BOOL pressed_by_keyboard = FALSE;

#015         if (hasFocus())

#016         {

#017             pressed_by_keyboard = gKeyboard->getKeyDown(' ') || (mCommitOnReturn && gKeyboard->getKeyDown(KEY_RETURN));

#018         }

#019 

 

没有选中的图片显示。

#020         // Unselected image assignments

#021         S32 local_mouse_x;

#022         S32 local_mouse_y;

#023         LLCoordWindow cursor_pos_window;

#024         getWindow()->getCursorPosition(&cursor_pos_window);

#025         LLCoordGL cursor_pos_gl;

#026         getWindow()->convertCoords(cursor_pos_window, &cursor_pos_gl);

#027         cursor_pos_gl.mX = llround((F32)cursor_pos_gl.mX / LLUI::sGLScaleFactor.mV[VX]);

#028         cursor_pos_gl.mY = llround((F32)cursor_pos_gl.mY / LLUI::sGLScaleFactor.mV[VY]);

#029         screenPointToLocal(cursor_pos_gl.mX, cursor_pos_gl.mY, &local_mouse_x, &local_mouse_y);

#030 

 

按下显示的处理，主要选择不同的图片。

#031         BOOL pressed = pressed_by_keyboard

#032                         || (hasMouseCapture() && pointInView(local_mouse_x, local_mouse_y))

#033                         || mToggleState;

#034        

#035         BOOL use_glow_effect = FALSE;

#036         if ( mNeedsHighlight || flash )

#037         {

#038             if (pressed)

#039             {

#040                 if (mImageHoverSelected)

#041                 {

#042                     mImagep = mImageHoverSelected;

#043                 }

#044                 else

#045                 {

#046                     mImagep = mImageSelected;

#047                     use_glow_effect = TRUE;

#048                 }

#049             }

#050             else

#051             {

#052                 if (mImageHoverUnselected)

#053                 {

#054                     mImagep = mImageHoverUnselected;

#055                 }

#056                 else

#057                 {

#058                     mImagep = mImageUnselected;

#059                     use_glow_effect = TRUE;

#060                 }

#061             }

#062         }

#063         else if ( pressed )

#064         {

#065             mImagep = mImageSelected;

#066         }

#067         else

#068         {

#069             mImagep = mImageUnselected;

#070          }

#071 

#072         // Override if more data is available

#073         // HACK: Use gray checked state to mean either:

#074         //   enabled and tentative

#075         // or

#076         //   disabled but checked

 

保存选择的显示图片。

#077         if (!mImageDisabledSelected.isNull() && ( (getEnabled() && getTentative()) || (!getEnabled() && pressed ) ) )

#078         {

#079             mImagep = mImageDisabledSelected;

#080         }

#081         else if (!mImageDisabled.isNull() && !getEnabled() && !pressed)

#082         {

#083             mImagep = mImageDisabled;

#084         }

#085 

#086         if (mNeedsHighlight && !mImagep)

#087         {

#088             use_glow_effect = TRUE;

#089         }

#090 

#091         // Figure out appropriate color for the text

#092         LLColor4 label_color;

#093 

 

获取按钮显示的颜色。

#094         // label changes when button state changes, not when pressed

#095         if ( getEnabled() )

#096         {

#097             if ( mToggleState )

#098             {

#099                 label_color = mSelectedLabelColor;

#100             }

#101             else

#102             {

#103                 label_color = mUnselectedLabelColor;

#104             }

#105         }

#106         else

#107         {

#108             if ( mToggleState )

#109             {

#110                 label_color = mDisabledSelectedLabelColor;

#111             }

#112             else

#113             {

#114                 label_color = mDisabledLabelColor;

#115             }

#116         }

#117 

 

准备显示的字符串。

#118         // Unselected label assignments

#119         LLWString label;

#120 

#121         if( mToggleState )

#122         {

#123             if( getEnabled() || mDisabledSelectedLabel.empty() )

#124             {

#125                 label = mSelectedLabel;

#126             }

#127             else

#128             {

#129                 label = mDisabledSelectedLabel;

#130             }

#131         }

#132         else

#133         {

#134             if( getEnabled() || mDisabledLabel.empty() )

#135             {

#136                 label = mUnselectedLabel;

#137             }

#138             else

#139             {

#140                 label = mDisabledLabel;

#141             }

#142         }

#143 

#144         //测试一下。

#145         //label = L"测试 ";

#146        

 

显示按钮的边界。

#147         // draw default button border

#148         if (getEnabled() && mBorderEnabled && gFocusMgr.getAppHasFocus()) // because we're the default button in a panel

#149         {

#150             drawBorder(LLUI::sColorsGroup->getColor( "ButtonBorderColor" ), BORDER_SIZE);

#151         }

#152 

#153         // overlay with keyboard focus border

#154         if (hasFocus())

#155         {

#156              F32 lerp_amt = gFocusMgr.getFocusFlashAmt();

#157             drawBorder(gFocusMgr.getFocusColor(), llround(lerp(1.f, 3.f, lerp_amt)));

#158         }

#159        

#160         if (use_glow_effect)

#161         {

#162             mCurGlowStrength = lerp(mCurGlowStrength, mHoverGlowStrength, LLCriticalDamp::getInterpolant(0.05f));

#163         }

#164         else

#165         {

#166             mCurGlowStrength = lerp(mCurGlowStrength, 0.f, LLCriticalDamp::getInterpolant(0.05f));

#167         }

#168 

#169         // Draw button image, if available.

#170         // Otherwise draw basic rectangular button.

#171         if( mImagep.notNull() && !mScaleImage)

#172         {

#173             mImagep->draw(0, 0, getEnabled() ? mImageColor : mDisabledImageColor );

#174             if (mCurGlowStrength > 0.01f)

#175             {

#176                 gGL.blendFunc(GL_SRC_ALPHA, GL_ONE);

#177                 mImagep->drawSolid(0, 0, LLColor4(1.f, 1.f, 1.f, mCurGlowStrength));

#178                 gGL.blendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

#179             }

#180         }

#181         else

#182         if ( mImagep.notNull() && mScaleImage)

#183         {

#184             mImagep->draw(0, 0, getRect().getWidth(), getRect().getHeight(), getEnabled() ? mImageColor : mDisabledImageColor );

#185             if (mCurGlowStrength > 0.01f)

#186             {

#187                 gGL.blendFunc(GL_SRC_ALPHA, GL_ONE);

#188                 mImagep->drawSolid(0, 0, getRect().getWidth(), getRect().getHeight(), LLColor4(1.f, 1.f, 1.f, mCurGlowStrength));

#189                 gGL.blendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

#190             }

#191         }

#192         else

#193         {

#194             // no image

#195             llwarns << "No image for button " << getName() << llendl;

#196             // draw it in pink so we can find it

#197             gl_rect_2d(0, getRect().getHeight(), getRect().getWidth(), 0, LLColor4::pink1, FALSE);

#198         }

#199 

 

计算显示字符串的位置。

#200         // let overlay image and text play well together

#201         S32 text_left = mLeftHPad;

#202         S32 text_right = getRect().getWidth() - mRightHPad;

#203         S32 text_width = getRect().getWidth() - mLeftHPad - mRightHPad;

#204 

#205         // draw overlay image

#206         if (mImageOverlay.notNull())

#207         {

#208             // get max width and height (discard level 0)

#209             S32 overlay_width = mImageOverlay->getWidth();

#210             S32 overlay_height = mImageOverlay->getHeight();

#211 

#212              F32 scale_factor = llmin((F32)getRect().getWidth() / (F32)overlay_width, (F32)getRect().getHeight() / (F32)overlay_height, 1.f);

#213             overlay_width = llround((F32)overlay_width * scale_factor);

#214             overlay_height = llround((F32)overlay_height * scale_factor);

#215 

#216             S32 center_x = getLocalRect().getCenterX();

#217             S32 center_y = getLocalRect().getCenterY();

#218 

#219             //FUGLY HACK FOR "DEPRESSED" BUTTONS

#220             if (pressed)

#221             {

#222                 center_y--;

#223                 center_x++;

#224             }

#225 

#226             // fade out overlay images on disabled buttons

#227             LLColor4 overlay_color = mImageOverlayColor;

#228             if (!getEnabled())

#229             {

#230                 overlay_color.mV[VALPHA] = 0.5f;

#231             }

#232 

#233              switch(mImageOverlayAlignment)

#234             {

#235             case LLFontGL::LEFT:

#236                 text_left += overlay_width + 1;

#237                 text_width -= overlay_width + 1;

#238                 mImageOverlay->draw(

#239                     mLeftHPad,

#240                     center_y - (overlay_height / 2),

#241                     overlay_width,

#242                     overlay_height,

#243                     overlay_color);

#244                 break;

#245             case LLFontGL::HCENTER:

#246                 mImageOverlay->draw(

#247                     center_x - (overlay_width / 2),

#248                     center_y - (overlay_height / 2),

#249                     overlay_width,

#250                     overlay_height,

#251                     overlay_color);

#252                 break;

#253             case LLFontGL::RIGHT:

#254                 text_right -= overlay_width + 1;               

#255                 text_width -= overlay_width + 1;

#256                 mImageOverlay->draw(

#257                      getRect().getWidth() - mRightHPad - overlay_width,

#258                     center_y - (overlay_height / 2),

#259                     overlay_width,

#260                     overlay_height,

#261                     overlay_color);

#262                 break;

#263             default:

#264                 // draw nothing

#265                 break;

#266             }

#267         }

#268 

 

显示按钮的字符串。

#269         // Draw label

#270         if( !label.empty() )

#271         {

#272             LLWString::trim(label);

#273 

#274             S32 x;

#275             switch( mHAlign )

#276             {

#277             case LLFontGL::RIGHT:

#278                 x = text_right;

#279                 break;

#280             case LLFontGL::HCENTER:

#281                 x = getRect().getWidth() / 2;

#282                 break;

#283             case LLFontGL::LEFT:

#284             default:

#285                 x = text_left;

#286                 break;

#287             }

#288 

#289             S32 y_offset = 2 + (getRect().getHeight() - 20)/2;

#290        

#291             if (pressed)

#292             {

#293                 y_offset--;

#294                 x++;

#295             }

#296 

 

主要调用 OPENGL里的字体处理类来显示字符串。

#297             mGLFont->render(label, 0, (F32)x, (F32)(LLBUTTON_V_PAD + y_offset),

#298                 label_color,

#299                 mHAlign, LLFontGL::BOTTOM,

#300                 mDropShadowedText ? LLFontGL::DROP_SHADOW_SOFT : LLFontGL::NORMAL,

#301                 U32_MAX, text_width,

#302                 NULL, FALSE, FALSE);

#303         }

#304 

#305         if (sDebugRects

#306             || (LLView::sEditingUI && this == LLView::sEditingUIView))

#307         {

#308             drawDebugRect();

#309         }

#310     }

#311     // reset hover status for next frame

#312     mNeedsHighlight = FALSE;

#313 }

#314 

 

在这个函数里，先要选择按钮背景的图片，然后根据是否选中显示不同的图片，不同的颜色，最后调用 OPENGL处理的字体类来显示字符串，实现按钮的名称显示。