feat: add new stacking strategies

src/processor/dataStack.ts

@@ -39,13 +39,13 @@ type StackInfo = Pick<
 // (1) [Caution]: the logic is correct based on the premises:
 //     data processing stage is blocked in stream.
 //     See <module:echarts/stream/Scheduler#performDataProcessorTasks>
-// (2) Only register once when import repeatly.
-//     Should be executed after series filtered and before stack calculation.
+// (2) Only register once when import repeatedly.
+//     Should be executed after series is filtered and before stack calculation.
 export default function dataStack(ecModel: GlobalModel) {
     const stackInfoMap = createHashMap<StackInfo[]>();
     ecModel.eachSeries(function (seriesModel: SeriesModel<SeriesOption & SeriesStackOptionMixin>) {
         const stack = seriesModel.get('stack');
-        // Compatibal: when `stack` is set as '', do not stack.
+        // Compatible: when `stack` is set as '', do not stack.
         if (stack) {
             const stackInfoList = stackInfoMap.get(stack) || stackInfoMap.set(stack, []);
             const data = seriesModel.getData();
@@ -87,6 +87,7 @@ function calculateStack(stackInfoList: StackInfo[]) {
         const dims: [string, string] = [targetStackInfo.stackResultDimension, targetStackInfo.stackedOverDimension];
         const targetData = targetStackInfo.data;
         const isStackedByIndex = targetStackInfo.isStackedByIndex;
+        const stackStrategy = targetStackInfo.seriesModel.get('stackStrategy') || 'samesign';
 
         // Should not write on raw data, because stack series model list changes
         // depending on legend selection.
@@ -126,12 +127,16 @@ function calculateStack(stackInfoList: StackInfo[]) {
                     ) as number;
 
                     // Considering positive stack, negative stack and empty data
-                    if ((sum >= 0 && val > 0) // Positive stack
-                        || (sum <= 0 && val < 0) // Negative stack
+                    if (
+                        stackStrategy === 'all' // single stack group
+                        || (stackStrategy === 'positive' && val > 0)
+                        || (stackStrategy === 'negative' && val < 0)
+                        || (stackStrategy === 'samesign' && sum >= 0 && val > 0) // All positive stack
+                        || (stackStrategy === 'samesign' && sum <= 0 && val < 0) // All negative stack
                     ) {
-                        // The sum should be as less as possible to be effected
-                        // by floating arithmetic problem. A wrong result probably
-                        // filtered incorrectly by axis min/max.
+                        // The sum has to be very small to be affected by the
+                        // floating arithmetic problem. An incorrect result will probably
+                        // cause axis min/max to be filtered incorrectly.
                         sum = addSafe(sum, val);
                         stackedOver = val;
                         break;

src/util/types.ts

@@ -1661,6 +1661,7 @@ export interface SeriesLargeOptionMixin {
 }
 export interface SeriesStackOptionMixin {
     stack?: string
+    stackStrategy?: 'samesign' | 'all' | 'positive' | 'negative';
 }
 
 type SamplingFunc = (frame: ArrayLike<number>) => number;