Function prepare

src/renderers/createPieRenderer.ts:236–379

(seriesConfig, gridArea)

  };

  const prepare: PieRenderer['prepare'] = (seriesConfig, gridArea) => {
    assertNotDisposed();

    const dprRaw = gridArea.devicePixelRatio;
    const dpr = dprRaw > 0 && Number.isFinite(dprRaw) ? dprRaw : 1;

    lastCanvasWidth = gridArea.canvasWidth;
    lastCanvasHeight = gridArea.canvasHeight;
    writeVsUniforms(gridArea.canvasWidth, gridArea.canvasHeight);
    lastScissor = computePlotScissorDevicePx(gridArea);

    const canvasCssWidth = gridArea.canvasWidth / dpr;
    const canvasCssHeight = gridArea.canvasHeight / dpr;
    if (!(canvasCssWidth > 0) || !(canvasCssHeight > 0)) {
      instanceCount = 0;
      return;
    }

    const plotWidthCss = canvasCssWidth - gridArea.left - gridArea.right;
    const plotHeightCss = canvasCssHeight - gridArea.top - gridArea.bottom;
    if (!(plotWidthCss > 0) || !(plotHeightCss > 0)) {
      instanceCount = 0;
      return;
    }

    const maxRadiusCss = 0.5 * Math.min(plotWidthCss, plotHeightCss);
    if (!(maxRadiusCss > 0)) {
      instanceCount = 0;
      return;
    }

    // Center specified in plot-local CSS px (or %), then shifted by GridArea CSS margins.
    const centerPlotCss = resolveCenterPlotCss(seriesConfig.center, plotWidthCss, plotHeightCss);
    const centerCanvasCssX = gridArea.left + centerPlotCss.x;
    const centerCanvasCssY = gridArea.top + centerPlotCss.y;

    // Instance center is in clip space; VS transform is identity.
    const centerClipX = (centerCanvasCssX / canvasCssWidth) * 2 - 1;
    const centerClipY = 1 - (centerCanvasCssY / canvasCssHeight) * 2;
    if (!Number.isFinite(centerClipX) || !Number.isFinite(centerClipY)) {
      instanceCount = 0;
      return;
    }

    // Radii specified in CSS px (or % of max radius), converted to device px for the shader.
    const radiiCss = resolveRadiiCss(seriesConfig.radius, maxRadiusCss);
    const innerCss = Math.max(0, Math.min(radiiCss.inner, radiiCss.outer));
    const outerCss = Math.max(innerCss, radiiCss.outer);
    const innerPx = innerCss * dpr;
    const outerPx = outerCss * dpr;
    if (!(outerPx > 0)) {
      instanceCount = 0;
      return;
    }

    // Total positive value for angle allocation.
    let total = 0;
    let validCount = 0;