C 语言链式调用与Tween算法实现(4)链式封装接口

来源：互联网发布：centos安装tengine 编辑：程序博客网时间：2024/05/18 05:15

在有上下文this指针的语言中，可以把this指针return出去。这样就可以形成一种链式调用的效果。配合上良好的方法命名，能够让函数功能的组合调用，使用起来非常的直觉化。在C语言中并没有this指针，所有的上下文对象需要，手动传入上下文对象。

以前介绍了3篇关于C语言如何实现tween缓动算法的。

C 实现通用Tween缓动动画(1)插值公式
C 实现通用Tween缓动动画(2)Tween数据结构

然而，函数的调用缺少链式调用非常的不流畅。而tween又很多默认参数的设定，往往链式调用能够更加方便的使用。

本文结合一种实现链式调用的方式，来在tween的实现之上进行一个链式调用的封装。我的思路很简单，链式调用需要上下文，C没有，那我们就要构造一个上下文以供使用。那我们看代码。

struct ATweenTool{    /**     * Create one TweenAction in context for chain setting     */struct ATweenTool* (*SetAction)       ();/** * Create action with no actionValue * just through duration time then callback */struct ATweenTool* (*SetInterval)     (float duration);//--------------------------------------------------------------------------------------------------// Create one TweenAction with TweenActionValue//--------------------------------------------------------------------------------------------------    struct ATweenTool* (*SetActionMoveX)  (float moveX,   float duration);    struct ATweenTool* (*SetActionMoveY)  (float moveY,   float duration);    struct ATweenTool* (*SetActionMove)   (float moveX,   float moveY,  float duration, bool isRelative, TweenEaseType easeType);    struct ATweenTool* (*SetActionScaleX) (float scaleX,  float duration);    struct ATweenTool* (*SetActionScaleY) (float scaleY,  float duration);    struct ATweenTool* (*SetActionScale)  (float scaleX,  float scaleY, float duration, bool isRelative, TweenEaseType easeType);    struct ATweenTool* (*SetActionRotateZ)(float rotateZ, float duration);    struct ATweenTool* (*SetActionFadeTo) (float fadeTo,  float duration);//--------------------------------------------------------------------------------------------------// After SetAction then set TweenAction property for current context created//--------------------------------------------------------------------------------------------------struct ATweenTool* (*SetDuration)     (float                     duration);struct ATweenTool* (*SetUserData)     (void*                     userData);struct ATweenTool* (*SetQueue)        (bool                      isQueue);struct ATweenTool* (*SetOnComplete)   (TweenActionOnComplete     OnComplete);struct ATweenTool* (*SetTarget)       (void*                     target);/** * Get TweenAction in current context */struct ATweenTool* (*GetAction)       (TweenAction**             outActionPtr);//--------------------------------------------------------------------------------------------------// Add new TweenActionValue into context TweenAction//--------------------------------------------------------------------------------------------------    struct ATweenTool* (*SetMoveX)        (float                     moveX);    struct ATweenTool* (*SetMoveY)        (float                     moveY);    struct ATweenTool* (*SetScaleX)       (float                     scaleX);    struct ATweenTool* (*SetScaleY)       (float                     scaleY);    struct ATweenTool* (*SetRotateZ)      (float                     rotateZ);    struct ATweenTool* (*SetFadeTo)       (float                     fadeTo);//--------------------------------------------------------------------------------------------------// After SetValue then set TweenActionValue property for current context created//--------------------------------------------------------------------------------------------------/** * After SetValue then SetRelative on new created TweenActiveValue */struct ATweenTool* (*SetRelative)     (bool                      isRelative);/** * After SetValue then SetEaseType on new created TweenActiveValue */struct ATweenTool* (*SetEaseType)     (TweenEaseType             easeType);//--------------------------------------------------------------------------------------------------/** * Run actions all in current context, set action target if has actionValue * and use target be tweenId */void               (*RunActions)      (void*                      target);/** * Run actions all in current context, action must set target * if has actionValue and return tweenId */void*              (*RunTargets)      ();};extern struct ATweenTool ATweenTool[1];

我们需要一个链式调用的发起者，通常是一个单例对象。这里就是有ATweenTool充当。可以看到，几乎所有的函数都会直接返回 ATweenTool结构指针，这样就可以在函数调用完成的时候，链式的调用所属的其它函数形成链式调用。ATweenTool的方法有3大类。

第一类，生成一个Action，以SetAction开头的函数以及SetInterval函数，都会生成一个上下文Action对象。以后针对Action属性的设置函数，比如SetDuration，SetUserData等等，都会使用这个上下文的Action，可以看到这些函数并没有传入Action对象作为参数。当重新SetAction的时候，上下文对象就会重置。

第二类，生成一个ActionValue，以SetMove，SetScale等等这样的函数，都会生成一个上下文的ActionValue对象。以后针对ActionValue属性的设置函数，比如SetRelative等函数，都会使用这个上下文的ActionValue，可以看到这些函数并没有传入ActionValue作为参数。当重新SetMove等时候，上下文对象就会重置。

第三类，RunActions和RunTargets两个函数，返回值不再是ATweenTool这样返回。意味着这是链式调用的终点。一旦调用Tween动画开始执行。

接下来，看看上下文是如何生成的。

#define action_length 30static Array(TweenAction*) actionArr[1] ={(TweenAction*[action_length]) {},0};static TweenAction*      action      = NULL;static TweenActionValue* actionValue = NULL;

就是简单的使用了一个static变量持有了Action数组。也就是说上下文Action的生成是有上限的。在执行tween动画执行之前，一共只能生成action_length个Action。那么，action和actionValue变量，就是记录了当前上下文的对象。随着新Action和ActionValue的设置，当前变量不断的被赋值。

#define CheckAction(tag) \ALogA(action      != NULL, "ATweenTool " tag " TweenAction not created");#define CheckActionValue(tag) \ALogA(actionValue != NULL, "ATweenTool " tag " TweenActionValue invalid");static struct ATweenTool* SetAction(){ALogA(actionArr->length <= action_length,"ATweenTool can not cache TweenActions = %d more than %d",actionArr->length,action_length);action      = ATween->GetAction();actionValue = NULL;AArraySet(actionArr,actionArr->length++,action,TweenAction*);return ATweenTool;}static inline struct ATweenTool* SetValue(TweenActionValueGetSet* valueGetSet, float value){    CheckAction("SetValue");    actionValue        = ATween->AddTweenActionValue(action);    actionValue->OnGet = valueGetSet->OnGet;    actionValue->OnSet = valueGetSet->OnSet;    actionValue->value = value;    return ATweenTool;}static struct ATweenTool* SetDuration(float duration){    CheckAction("SetDuration");    action->duration = duration;    return ATweenTool;}static struct ATweenTool* SetRelative(bool isRelative){    CheckAction     ("SetRelative");    CheckActionValue("SetRelative");    actionValue->isRelative = isRelative;    return ATweenTool;}static struct ATweenTool* SetEaseType(TweenEaseType easeType){    CheckAction     ("SetEaseType");    CheckActionValue("SetEaseType");    actionValue->easeType = easeType;    return ATweenTool;}static struct ATweenTool* SetInterval(float duration){    SetAction();    SetDuration(duration);    return ATweenTool;}//--------------------------------------------------------------------------------------------------static struct ATweenTool* SetActionMoveX(float moveX, float duration){    SetAction();    SetValue(ATweenActionValueGetSetImpl->moveX, moveX);    SetDuration(duration);    return ATweenTool;}static struct ATweenTool* SetActionMoveY(float moveY, float duration){    SetAction();    SetValue(ATweenActionValueGetSetImpl->moveY, moveY);    SetDuration(duration);    return ATweenTool;}static struct ATweenTool* SetActionMove(float moveX, float moveY, float duration, bool isRelative, TweenEaseType easeType){    SetAction  ();    SetValue   (ATweenActionValueGetSetImpl->moveX, moveX);    SetRelative(isRelative);    SetEaseType(easeType);    SetValue   (ATweenActionValueGetSetImpl->moveY, moveY);    SetRelative(isRelative);    SetEaseType(easeType);    SetDuration(duration);    return ATweenTool;}static struct ATweenTool* SetActionScaleX(float scaleX, float duration){    SetAction();    SetValue(ATweenActionValueGetSetImpl->scaleX, scaleX);    SetDuration(duration);    return ATweenTool;}static struct ATweenTool* SetActionScaleY(float scaleY, float duration){    SetAction();    SetValue(ATweenActionValueGetSetImpl->scaleY, scaleY);    SetDuration(duration);    return ATweenTool;}static struct ATweenTool* SetActionScale(float scaleX, float scaleY, float duration, bool isRelative, TweenEaseType easeType){    SetAction  ();    SetValue   (ATweenActionValueGetSetImpl->scaleX, scaleX);    SetRelative(isRelative);    SetEaseType(easeType);    SetValue   (ATweenActionValueGetSetImpl->scaleY, scaleY);    SetRelative(isRelative);    SetEaseType(easeType);    SetDuration(duration);    return ATweenTool;}static struct ATweenTool* SetActionRotateZ(float rotateZ, float duration){    SetAction();    SetValue(ATweenActionValueGetSetImpl->rotateZ, rotateZ);    SetDuration(duration);    return ATweenTool;}static struct ATweenTool* SetActionFadeTo(float fadeTo, float duration){    SetAction();    SetValue(ATweenActionValueGetSetImpl->fadeTo, fadeTo);    SetDuration(duration);    return ATweenTool;}//--------------------------------------------------------------------------------------------------static struct ATweenTool* SetUserData(void* userData){CheckAction("SetUserData");action->userData = userData;return ATweenTool;}static struct ATweenTool* SetQueue(bool isQueue){CheckAction("SetQueue");action->isQueue = isQueue;return ATweenTool;}static struct ATweenTool* SetOnComplete(TweenActionOnComplete OnComplete){CheckAction("SetOnComplete");action->OnComplete = OnComplete;return ATweenTool;}static struct ATweenTool* SetTarget(void* target){CheckAction("SetTarget");action->target = target;return ATweenTool;}static struct ATweenTool* GetAction(TweenAction** outActionPtr){CheckAction("GetAction");*outActionPtr = action;return ATweenTool;}//--------------------------------------------------------------------------------------------------static struct ATweenTool* SetMoveX(float moveX){    return SetValue(ATweenActionValueGetSetImpl->moveX, moveX);}static struct ATweenTool* SetMoveY(float moveY){    return SetValue(ATweenActionValueGetSetImpl->moveY, moveY);}static struct ATweenTool* SetScaleX(float scaleX){    return SetValue(ATweenActionValueGetSetImpl->scaleX, scaleX);}static struct ATweenTool* SetScaleY(float scaleY){    return SetValue(ATweenActionValueGetSetImpl->scaleY, scaleY);}static struct ATweenTool* SetRotateZ(float rotateZ){    return SetValue(ATweenActionValueGetSetImpl->rotateZ, rotateZ);}static struct ATweenTool* SetFadeTo(float fadeTo){    return SetValue(ATweenActionValueGetSetImpl->fadeTo, fadeTo);}//--------------------------------------------------------------------------------------------------static void RunActions(void* target){ALogA(target, "RunActions, target must not NULL");for (int i = 0; i < actionArr->length; i++){TweenAction* action = AArrayGet(actionArr, i, TweenAction*);if (action->actionValueList->size > 0){action->target = target;}}ATween->RunActions(actionArr, &target);actionArr->length = 0;    action            = NULL;actionValue       = NULL;}static void* RunTargets(){for (int i = 0; i < actionArr->length; i++){TweenAction* action = AArrayGet(actionArr, i, TweenAction*);if (action->actionValueList->size > 0){ALogA( action->target != NULL, "RunActions, the {%d} action has actionValue, so must set target", i);}}void* tweenId = NULL;ATween->RunActions(actionArr, &tweenId);actionArr->length = 0;    action            = NULL;actionValue       = NULL;    return tweenId;}struct ATweenTool ATweenTool[1] ={SetAction,SetInterval,    SetActionMoveX,    SetActionMoveY,    SetActionMove,    SetActionScaleX,    SetActionScaleY,    SetActionScale,    SetActionRotateZ,    SetActionFadeTo,SetDuration,SetUserData,SetQueue,SetOnComplete,SetTarget,GetAction,    SetMoveX,    SetMoveY,    SetScaleX,    SetScaleY,    SetRotateZ,    SetFadeTo,SetRelative,SetEaseType,RunActions,RunTargets,};#undef action_length#undef CheckAction#undef CheckActionValue

可以看到，所有链式调用的函数最后都会return ATweenTool结构。但执行tween动画以后，就会重置当前的上下文变量。那么，使用起来是一下这个样子的。

ATweenTool->SetActionMoveX(deltaX * 0.95f, enemy->hurtXTime)  ->SetEaseType   (tween_ease_quad_in)  ->SetQueue      (false)  ->SetOnComplete (AttackOnComplete)  ->SetUserData   (enemy)  ->SetActionMoveY(0.03f, enemy->hurtYUpTime)  ->SetEaseType   (tween_ease_quad_in)  ->SetActionMoveY(-0.03f, enemy->hurtYDownTime)  ->SetEaseType   (tween_ease_quad_out)  ->RunActions    (enemyDrawable);

最后给出，额外辅助的结构。

typedef struct{TweenActionValueOnGet OnGet;TweenActionValueOnSet OnSet;}TweenActionValueGetSet;struct ATweenActionValueGetSetImpl{    TweenActionValueGetSet moveX  [1];    TweenActionValueGetSet moveY  [1];    TweenActionValueGetSet scaleX [1];    TweenActionValueGetSet scaleY [1];    TweenActionValueGetSet rotateZ[1];    TweenActionValueGetSet fadeTo [1];};/** * Application must implement tween action value get set method */extern struct ATweenActionValueGetSetImpl ATweenActionValueGetSetImpl[1];

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