COCOS2D-X屏幕适配

原文地址：http://www.cocos2d-x.org/wiki/Multi_resolution_support

Multi-resolution support

The APIs used in this document are available sincecocos2d-2.0-x-2.0.4.

Multi-resolution support

The principle

designResolutionSize

contentScaleFactor

Policies

Exact fit

No border

Show all

Fixed Height

Fixed Width

External Links

The diverse set of resolutions on Android devices is hard to adaptto. Cocos2d-x offers

CCEGLView::setDesignResolutionSize()

and

CCDirector::setContentScaleFactor()

tohelp
your game run on different resolutions with minimal amount ofwork.

The principle

We have removed all the codes relatedto

enableRetina

methodsince
v2.0.4. So Retina disappears since cocos2d-2.0-x-2.0.4. OniOS, if the device supports retina display, we enable it bydefault.

Therefore, you can get the real screen sizeby

CCEGLView::sharedOpenGLView()->getFrameSize()

.For
example, the function returns '960x640' for Iphone4S inlandscape mode.

But how to use the non-retina coordinates for retina devices? Thereare two concepts you have to know. One isdesignResolutionSize,another
is contentScaleFactor.

designResolutionSize

All your game's coordinates rely on design resolution no matterwhat the size of your device screen. If the UI layout of your gameis the same on all resolutions, you just need only a set ofcoordinates. Design resolution is set by

CCEGLView::sharedOpenGLView()->setDesignResolutionSize(width,height,
policy)

, the first and second parameters are thewidth and height of design resoultion and the third parameter isthe policy you want to use. I will explain the third parameterlater.

You could also use more than one set of resources on differentdevices to make a better display by

searchPath.push_back(largeResource.directory);

,

but you must set the contentScaleFactor too.

Here are some code snippets in HelloCpp project.

[code] 1typedef struct tagResource
2{
3    cocos2d::CCSize size;
4    char directory[100];
5}Resource;
6
7static Resource smallResource  =  { cocos2d::CCSizeMake(480, 320),   "iphone" };
8static Resource mediumResource =  { cocos2d::CCSizeMake(1024, 768),  "ipad"   };
9static Resource largeResource  =  { cocos2d::CCSizeMake(2048, 1536), "ipadhd" };
10static cocos2d::CCSize designResolutionSize = cocos2d::CCSizeMake(480, 320);
11

[/code]

[code] 1bool AppDelegate::applicationDidFinishLaunching() {
2    // initialize director
3    CCDirector* pDirector = CCDirector::sharedDirector();
4    CCEGLView* pEGLView = CCEGLView::sharedOpenGLView();
5
6    pDirector->setOpenGLView(pEGLView);
7
8    // Set the design resolution
9    pEGLView->setDesignResolutionSize(designResolutionSize.width, designResolutionSize.height, kResolutionNoBorder);
10
11    CCSize frameSize = pEGLView->getFrameSize();
12
13    // In this demo, we select resource according to the frame's height.
14    // If the resource size is different from design resolution size, you need to set contentScaleFactor.
15    // We use the ratio of resource's height to the height of design resolution,
16    // this can make sure that the resource's height could fit for the height of design resolution.
17
18    // if the frame's height is larger than the height of medium resource size, select large resource.
19    if (frameSize.height > mediumResource.size.height)
20    {
21        searchPath.push_back(largeResource.directory);
22        pDirector->setContentScaleFactor(largeResource.size.height/designResolutionSize.height);
23    }
24    // if the frame's height is larger than the height of small resource size, select medium resource.
25    else if (frameSize.height > smallResource.size.height)
26    {
27        searchPath.push_back(mediumResource.directory);
28        pDirector->setContentScaleFactor(mediumResource.size.height/designResolutionSize.height);
29    }
30    // if the frame's height is smaller than the height of medium resource size, select small resource.
31    else
32    {
33        searchPath.push_back(smallResource.directory);
34        pDirector->setContentScaleFactor(smallResource.size.height/designResolutionSize.height);
35    }
36    ...................
37    ...................
38}

[/code]

contentScaleFactor

ContentScaleFactor describes the ratiofrom ResourcesSize to designResolutionSize.Normally,
it can be set by'ResourceBackGround.height/DesignResolution.height' or'ResourceBackGround.width/DesignResolution.width'. To choose whichone is based on your game design.

For illustration below, we use height to calculate thefactor.



Chart 1: ResourceSize
= 960x640 ; Design Resolution Size = 480x320 ; Target DeviceScreen Size = 800x480 ; RH/DH=RW/DW=2.0f; NoBorder Policy

When using NoBorder mode, there are some areas of the backgroud outof scope. If you use absolute coordinates based on designresolution size(480x320),

some of your game UI will not be shown completely. To resolve thisissue, you have to make the coordinates base on 'visiblerectangle'. You can get the origin point of 'visible rectange' by'CCDirector::sharedDirector()->getVisibleOrign()'.

Together with'CCDirector::sharedDirector()->getVisibleSize()',you will beable to confirm 9 points on the screen. They are 'Left','Right','Top','Bottom','Center','LeftTop','RightTop','LeftBottom' and'RightBottom'.

Your game will be really full screen display if all the coordinatesof your game is base on these ninepoints.

About how to calculate these points, please refer to 'VisibleRect'class in TestCpp project.



Chart 2: ResourceSize
= 1024x768 ; Design Resolution Size = 480x320 ; Target DeviceScreen Size = 800x480 ; RH/DH != RW/DW; NoBorder Policy

When RH/DH isn't equal to RW/RH, You should decide to select Widthor Height ratio of resource to design resolution.

In the chart 2, we still use height ratio to calculatecontentScaleFator, so the height of the resource background willfill for the height of design resolution.

Mark① shows two black rectangle will be in designresolution.

After mapping design resolution to screen, Mark① --> Mark②, andMark③ will be out of screen.

Now, you have two choices to make your game becomes full screen.One is to make your background picture wider.

Another is to set the contentScaleFactor based on the ratio ofwidth.

Policies

Now cocos2d-x supports five different policies.

Exact fit

The entire application is visible in the specified area withouttrying to preserve the original aspect ratio. Distortion can occur,and the application may appear stretched or compressed.

No border

The entire application fills the specified area, without distortionbut possibly with some cropping, while maintaining the originalaspect ratio of the application.

Show all

The entire application is visible in the specified area withoutdistortion while maintaining the original aspect ratio of theapplication. Borders can appear on two sides of theapplication.



Chart 3: ResourceSize
= 1024x768 ; Design Resolution Size = 480x320 ; Target DeviceScreen Size = 800x480 ; RH/DH != RW/DW; ShowAll Policy

Mark② and Mark③ are both black rectangle areas. But they aredifferent, Mark③ is out of Opengl Viewport, so you can't put anygame elements onto it.

Mark② appears because RW/RH isn'tequal to DW/DH,it's
in the Opengl Viewport， you can place your game elements ontoit.

Fixed Height

The width parameter of the design resolution size is ignored andrecalculated based on the height of the design resolution and theaspect ratio of the device.

The entire application is visible without distortion. Howeverdevelopers must make sure that they design their UI to matchdifferent aspect ratios.

Using this resolution policy will give you a different window widthacross devices, the window height is fixed. The visibility rectwill start at 0/0.

Example:
Device Resolution: 800x480px
Design Resolution: 480x320px
CCDirector Window Origin: 0/0
CCDirector Window Size: 534x320px

Device Resolution: 854x480px
Design Resolution: 480x320px
CCDirector Window Origin: 0/0
CCDirector Window Size: 570x320px

Device Resolution: 1024x768px
Design Resolution: 480x320px
CCDirector Window Origin: 0/0
CCDirector Window Size: 427x320px

As you can see the height of the display stays the same on allpossible device resolutions, only the window width will be adjustedto match the device aspect ratio.

In general you can use this mode like the No Boder mode, but thereis no need to use VisibleRect methods. If you place a sprite at(0/0) it will always

be in the lower left corner of the screen, If you place the spriteat (winSize.width/2, winSize.height/2) it will be in the center ofthe screen.

If you place the spite at (winSize.width/0) it will be at the lowerright border of the screen.

Avaiable since cocos2d-x v2.1rc0-x-2.1.3

Fixed Width

This mode works the same as the fixed height mode. The differenceis, that this mode will ignore the height of the design resolutionsize and recalcualte the height depending

on the device aspect ratio.

While the fixed height mode is useful for landscape games, you maywant to prefer this resolution policy for portrait games.

Avaiable since cocos2d-x v2.1rc0-x-2.1.3

You need to use relative coordinates only inNoBorder, FixedHeight and FixedWidth mode. Generally, developeruses NoBorder
mode for better display

External Links

TBD