RectTranform通用位置大小工具

# 最简单的就是，直接将anchor先设为center-mid，然后再设置位置大小

public static void SetAnchoredPos(RectTransform rtf, float x, float y)
{
    var v2Mid = Vector2.one * 0.5f;
    rtf.anchorMin = v2Mid;
    rtf.anchorMax = v2Mid;
    var v2 = rtf.anchoredPosition;
    v2.x = x;
    v2.y = y;
    rtf.anchoredPosition = v2;
}

public static void SetSize(RectTransform rtf, float w, float h)
{
    var size = rtf.sizeDelta;
    size.Set(w, h);
    rtf.sizeDelta = size;
}

 

# 不调整原来的anchor设置，通过left-top边距来调整RectTramsform的位置

/// <summary>
/// 移动到left-top边距处(与parent的left和top边, 不是anchor边), 保持大小不变
/// </summary>
public static void MoveByLeftTopMargin(RectTransform self, float leftMargin, float topMargin)
{
    MoveByLeftTopMargin(self, leftMargin, topMargin, (RectTransform) self.parent);
}

public static void MoveByLeftTopMargin(RectTransform self, float leftMargin, float topMargin, RectTransform parentRtf)
{
    var sizeDelta = self.sizeDelta;
    var rect = self.rect;
    var parentRect = parentRtf.rect;

    var offsetMin = self.offsetMin;
    var offsetMax = self.offsetMax;

    var anchorMin = self.anchorMin;

    var newLeftAnchorMargin = leftMargin - anchorMin.x * parentRect.width;
    newLeftAnchorMargin -= rect.width * 0.5f * (1 - self.localScale.x);
    if (sizeDelta.x <= 0) //x方向拉伸
    {
        var marginDiff = newLeftAnchorMargin - offsetMin.x /* oldAnchorMargin */;
        offsetMax.x += marginDiff;
    }
    else
    {
        offsetMax.x = newLeftAnchorMargin + rect.width;
    }

    offsetMin.x = newLeftAnchorMargin;


    var anchorMax = self.anchorMax;

    var newTopAnchorMargin = topMargin - (1 - anchorMax.y) * parentRect.height;
    newTopAnchorMargin -= rect.height * 0.5f * (1 - self.localScale.y);
    if (sizeDelta.y <= 0) //y方向拉伸
    {
        var marginDiff = -newTopAnchorMargin - offsetMax.y /* oldAnchorMargin */;
        offsetMin.y += marginDiff;
    }
    else
    {
        offsetMin.y = -newTopAnchorMargin - rect.height;
    }

    offsetMax.y = -newTopAnchorMargin; //我们的margin是parent内部为正, 外部为负; unity的top offset是向上为正, 向下为负

    self.offsetMin = offsetMin;
    self.offsetMax = offsetMax;
}

# 获取边距

/// <summary>
/// 获取与parent的边距(非anchor边), 在parent内部为正, 在parent外部为负
/// </summary>
public static float GetMarginLeft(RectTransform self)
{
    return GetMarginLeft(self, (RectTransform) self.parent);
}
public static float GetMarginLeft(RectTransform self, RectTransform parentRtf)
{
    var parentRect = parentRtf.rect;
    return self.offsetMin.x + (self.anchorMin.x * parentRect.width);
}

/// <summary>
/// 获取与parent的边距(非anchor边), 在parent内部为正, 在parent外部为负
/// </summary>
public static float GetMarginTop(RectTransform self)
{
    return GetMarginTop(self, (RectTransform) self.parent);
}
public static float GetMarginTop(RectTransform self, RectTransform parentRtf)
{
    var parentRect = parentRtf.rect;
    return -self.offsetMax.y + (1 - self.anchorMax.y) * parentRect.height;
}

/// <summary>
/// 获取与parent的边距(非anchor边), 在parent内部为正, 在parent外部为负
/// </summary>
public static float GetMarginRight(RectTransform self)
{
    return GetMarginRight(self, (RectTransform) self.parent);
}
public static float GetMarginRight(RectTransform self, RectTransform parentRtf)
{
    var parentRect = parentRtf.rect;
    return -self.offsetMax.x + (1 - self.anchorMax.x) * parentRect.width;
}

/// <summary>
/// 获取与parent的边距(非anchor边), 在parent内部为正, 在parent外部为负
/// </summary>
public static float GetMarginBottom(RectTransform self)
{
    return GetMarginBottom(self, (RectTransform) self.parent);
}
public static float GetMarginBottom(RectTransform self, RectTransform parentRtf)
{
    var parentRect = parentRtf.rect;
    return self.offsetMin.y + self.anchorMin.y * parentRect.height;
}

 

# 设置大小

/// <param name="leftDiff">向左为负, 向右为正</param>
/// <param name="rightDiff">向左为负, 向右为正</param>
/// <param name="topDiff">向上为正, 向下为负</param>
/// <param name="bottomDiff">向上为正, 向下为负</param>
public static void SetSizeByDiff(RectTransform rtf, float leftDiff, float rightDiff, float topDiff, float bottomDiff)
{
    var offsetMin = rtf.offsetMin;
    var offsetMax = rtf.offsetMax;

    offsetMin.x += leftDiff;
    offsetMax.x += rightDiff;

    offsetMin.y += bottomDiff;
    offsetMax.y += topDiff;

    rtf.offsetMin = offsetMin;
    rtf.offsetMax = offsetMax;
}


public static void SetSize(RectTransform rtf, float w, float h)
{
    var sizeDelta = rtf.sizeDelta;

    if (sizeDelta.x <= 0 && sizeDelta.y <= 0) //x, y都拉伸
    {
        var offsetMin = rtf.offsetMin;
        var offsetMax = rtf.offsetMax;
        var parentRectTrans = rtf.parent as RectTransform;
        if (null != parentRectTrans)
        {
            offsetMax.x = w + offsetMin.x - parentRectTrans.rect.width;
            offsetMax.y = h + offsetMin.y - parentRectTrans.rect.height;

            rtf.offsetMax = offsetMax;
        }
    }

    if (sizeDelta.x > 0 && sizeDelta.y > 0)
    {
        sizeDelta.x = w;
        sizeDelta.y = h;
        rtf.sizeDelta = sizeDelta;
    }
    else if (sizeDelta.x > 0) //x方向正常, y方向拉伸
    {
        sizeDelta.x = w;
        rtf.sizeDelta = sizeDelta;

        //y方向拉伸
        var offsetMin = rtf.offsetMin;
        var offsetMax = rtf.offsetMax;
        var parentRectTrans = rtf.parent as RectTransform;
        if (null != parentRectTrans)
        {
            //根据: dst-height = parentRectTrans.rect.height + offsetMax.y - offsetMin.y
            offsetMax.y = h + offsetMin.y - parentRectTrans.rect.height;
            rtf.offsetMax = offsetMax;
        }
    }
    else if (sizeDelta.y > 0) //x方向拉伸, y方向正常
    {
        //x方向拉伸
        var offsetMin = rtf.offsetMin;
        var offsetMax = rtf.offsetMax;
        var parentRectTrans = rtf.parent as RectTransform;
        if (null != parentRectTrans)
        {
            //根据: dst-width = parentRectTrans.rect.width + offsetMax.x - offsetMin.x
            offsetMax.x = w + offsetMin.x - parentRectTrans.rect.width;
            rtf.offsetMax = offsetMax;
        }

        sizeDelta.y = h;
        rtf.sizeDelta = sizeDelta;
    }
}