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。