From 86bc3e612d009c35b7858ccd72ed80fb3329b9bc Mon Sep 17 00:00:00 2001
From: Elias Naur <mail@eliasnaur.com>
Date: Fri, 5 Jul 2019 16:52:13 +0200
Subject: [PATCH] ui/text: use BlockOp as materials

Before this change, clients were expected to set up the current
material (color or image) before laying out Labels and Editors.
This was done to avoid garbage from a hypothetical material
interface covering both colors and images.

However, some widgets need more than one material: the Editor had
HintImage for the hint text material.

This change implements generalized materials through blocks:
anywhere a material is expected, a ui.BlockOp is is assumed to
contain the operation(s) needed for setting the desired material.

This way we avoid allocations (interfaces) and keep the
abstraction over material types.

Signed-off-by: Elias Naur <mail@eliasnaur.com>
---
 ui/ops.go         |  3 +++
 ui/text/editor.go | 13 ++++++++-----
 ui/text/label.go  |  2 ++
 3 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/ui/ops.go b/ui/ops.go
index f4728179..570c9067 100644
--- a/ui/ops.go
+++ b/ui/ops.go
@@ -213,6 +213,9 @@ func (b *BlockOp) decode(data []byte, refs []interface{}) {
 }
 
 func (b BlockOp) Add(o *Ops) {
+	if b.ops == nil {
+		return
+	}
 	data := make([]byte, ops.TypeBlockLen)
 	data[0] = byte(ops.TypeBlock)
 	bo := binary.LittleEndian
diff --git a/ui/text/editor.go b/ui/text/editor.go
index 9964ef67..9dacacb2 100644
--- a/ui/text/editor.go
+++ b/ui/text/editor.go
@@ -27,8 +27,9 @@ type Editor struct {
 	SingleLine bool
 	Submit     bool
 
-	Hint      string
-	HintImage image.Image
+	Material     ui.BlockOp
+	Hint         string
+	HintMaterial ui.BlockOp
 
 	oldCfg            ui.Config
 	blinkStart        time.Time
@@ -202,8 +203,10 @@ func (e *Editor) Layout(ops *ui.Ops, cs layout.Constraints) layout.Dimens {
 		Offset:    off,
 	}
 	ui.PushOp{}.Add(ops)
-	if e.HintImage != nil && e.rr.len() == 0 {
-		draw.ImageOp{Img: e.HintImage, Rect: e.HintImage.Bounds()}.Add(ops)
+	if e.rr.len() > 0 {
+		e.Material.Add(ops)
+	} else {
+		e.HintMaterial.Add(ops)
 	}
 	for {
 		str, lineOff, ok := e.it.Next()
@@ -216,7 +219,6 @@ func (e *Editor) Layout(ops *ui.Ops, cs layout.Constraints) layout.Dimens {
 		draw.DrawOp{Rect: toRectF(clip).Sub(lineOff)}.Add(ops)
 		ui.PopOp{}.Add(ops)
 	}
-	ui.PopOp{}.Add(ops)
 	if e.focused {
 		now := e.Config.Now
 		dt := now.Sub(e.blinkStart)
@@ -246,6 +248,7 @@ func (e *Editor) Layout(ops *ui.Ops, cs layout.Constraints) layout.Dimens {
 			redraw.Add(ops)
 		}
 	}
+	ui.PopOp{}.Add(ops)
 
 	baseline := e.padTop + e.dims.Baseline
 	pointer.AreaRect(e.viewSize).Add(ops)
diff --git a/ui/text/label.go b/ui/text/label.go
index b4587477..3684310c 100644
--- a/ui/text/label.go
+++ b/ui/text/label.go
@@ -17,6 +17,7 @@ import (
 
 type Label struct {
 	Face      Face
+	Material  ui.BlockOp
 	Alignment Alignment
 	Text      string
 	MaxLines  int
@@ -108,6 +109,7 @@ func (l Label) Layout(ops *ui.Ops, cs layout.Constraints) layout.Dimens {
 		ui.PushOp{}.Add(ops)
 		ui.TransformOp{Transform: ui.Offset(off)}.Add(ops)
 		l.Face.Path(str).Add(ops)
+		l.Material.Add(ops)
 		draw.DrawOp{Rect: lclip}.Add(ops)
 		ui.PopOp{}.Add(ops)
 	}