Charts - Dynamic change of color (cl_gui_chart_engine set_customizing) ST

Question

Dear all,
I want to influence the colors in chart which I created via class cl_gui_chart_engine. The first time I call the chart the columns are displayed in the desired colours (column 1 =  green / column 2 = red). BUT,when I influence the global variable g_trn  at runtime (see coding) I don't get the expected result (column 1 = red / column 2 = green). Other paramters (like title) work, but the colours somehow do not change. Any ideas? I guess I'm not the only one out there who wants a chart with GREEN (positive) and RED (negative) columns / lines...
Thanks & kind regards Benno
CONSTANTS: c_color_green(14) type c value 'RGB(60,248,80)',
                       c_color_red(14)   type c value 'RGB(248,80,60)'.
  IF g_trn IS INITIAL.
    l_color_1 = c_color_red.
    l_color_2 = c_color_green.
  ELSE.
    l_color_1 = c_color_green.
    l_color_2 = c_color_red.
  ENDIF.
  CLEAR l_xstr.
  CALL TRANSFORMATION z_gui_chart_engine_layout
      SOURCE title               = g_bupa
             category_axis_title = 'Time'
             value_axis_title    = 'Volume'
             chart_type          = 'Columns'   
             dimension           = 'PseudoTwo'
             colorpalette        = 'Tradeshow'
             color_1             = l_color_1
             color_2             = l_color_2
      RESULT XML l_xstr.
  g_viewer_r4->set_customizing( xdata = l_xstr ).
  CALL METHOD g_viewer_r4->render.
Transformation:
<?sap.transform simple?>
<tt:transform xmlns:tt="http://www.sap.com/transformation-templates">
  <tt:root name="CHART_TYPE"/>
  <tt:root name="DIMENSION"/>
  <tt:root name="TITLE"/>
  <tt:root name="CATEGORY_AXIS_TITLE"/>
  <tt:root name="VALUE_AXIS_TITLE"/>
  <tt:root name="COLORPALETTE"/>
  <tt:root name="COLOR_1"/>
  <tt:root name="COLOR_2"/>
  <tt:template>
    <SAPChartCustomizing version="2.1">
      <GlobalSettings>
        <ColorPalette>
          <tt:value ref="COLORPALETTE"/>
        </ColorPalette>
        <Dimension>
          <tt:value ref="DIMENSION"/>
        </Dimension>
        <Defaults>
          <ChartType>
            <tt:value ref="CHART_TYPE"/>
          </ChartType>
        </Defaults>
      </GlobalSettings>
      <Elements>
        <ChartElements>
          <Title>
            <Caption>
              <tt:value ref="TITLE"/>
            </Caption>
            <Text>
              <Size>14</Size>
            </Text>
          </Title>
        </ChartElements>
        <ChartAxes>
          <CategoryAxis>
            <Title>
              <Caption>
                <tt:value ref="CATEGORY_AXIS_TITLE"/>
              </Caption>
            </Title>
          </CategoryAxis>
          <ValueAxis id="ValueAxis1">
            <Title>
              <Caption>
                <tt:value ref="VALUE_AXIS_TITLE"/>
              </Caption>
            </Title>
          </ValueAxis>
        </ChartAxes>
      </Elements>
      <Values>
        <Series id="Series1">
          <LineColor>
            <tt:value ref="COLOR_1"/>
          </LineColor>
          <Color>
            <tt:value ref="COLOR_1"/>
          </Color>
        </Series>
        <Series id="Series2">
          <LineColor>
            <tt:value ref="COLOR_2"/>
          </LineColor>
          <Color>
            <tt:value ref="COLOR_2"/>
          </Color>
        </Series>
      </Values>
    </SAPChartCustomizing>
  </tt:template>
</tt:transform>

Answer 1

I think it would work with CL_GUI_CHART_ENGINE_WIN but the RENDER method of CL_GUI_CHART_ENGINE checks if m_gui_control is initial, which probably isn't true ?