From 26b4a7e5a08713f7300e73da32ac6acb0772f3c6 Mon Sep 17 00:00:00 2001
From: Eric Hodel <drbrain@segment7.net>
Date: Wed, 20 Jun 2018 14:54:37 -0700
Subject: [PATCH] Pad formatted output when it gets shorter

When using the CurrentByte formatter the rendered progress bar may get
shorter.  When the current values advances from under 1MB to over 1MB
the bar should show "1024.00KB" then "1.00MB".

The output was not padded so the end result on the screen would look
like "1.00MB0KB" which was not easy to read and does not look nice.

Now the output is padded so the characters left over from the last
render are replaced by spaces so the result on the screen will look like
"1.00MB".

To accomplish this the existing ProgressBar#padout method is called from
ProgressBar#render and #padout is updated to use
ProgressBar#display_columns so the next render width is correctly
calculated.
---
 lib/tty/progressbar.rb         | 11 ++++++++---
 spec/unit/custom_token_spec.rb |  2 +-
 spec/unit/render_spec.rb       | 27 +++++++++++++++++++++++++++
 spec/unit/resize_spec.rb       |  2 +-
 4 files changed, 37 insertions(+), 5 deletions(-)
 create mode 100644 spec/unit/render_spec.rb

diff --git a/lib/tty/progressbar.rb b/lib/tty/progressbar.rb
index c47fd8a..cd7d85b 100644
--- a/lib/tty/progressbar.rb
+++ b/lib/tty/progressbar.rb
@@ -257,7 +257,10 @@ def render
       @tokens.each do |token, val|
         formatted = formatted.gsub(":#{token}", val)
       end
-      write(formatted, true)
+
+      padded = padout(formatted)
+
+      write(padded, true)
 
       @last_render_time  = Time.now
       @last_render_width = display_columns(formatted)
@@ -479,8 +482,10 @@ def inspect
     #
     # @api private
     def padout(message)
-      if @last_render_width > message.length
-        remaining_width = @last_render_width - message.length
+      message_length = display_columns(message)
+
+      if @last_render_width > message_length
+        remaining_width = @last_render_width - message_length
         message += ' ' * remaining_width
       end
       message
diff --git a/spec/unit/custom_token_spec.rb b/spec/unit/custom_token_spec.rb
index 923a43a..5a3835d 100644
--- a/spec/unit/custom_token_spec.rb
+++ b/spec/unit/custom_token_spec.rb
@@ -8,7 +8,7 @@
     output.rewind
     expect(output.read).to eq([
       "\e[1G(1) Hello Piotr!",
-      "\e[1G(4) Bye Piotr!\n"
+      "\e[1G(4) Bye Piotr!  \n"
     ].join)
   end
 end
diff --git a/spec/unit/render_spec.rb b/spec/unit/render_spec.rb
new file mode 100644
index 0000000..89f270f
--- /dev/null
+++ b/spec/unit/render_spec.rb
@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+RSpec.describe TTY::ProgressBar, "#render" do
+  let(:output) { StringIO.new(+"", "w+") }
+
+  it "pads out longer previous lines" do
+    progress = TTY::ProgressBar.new ":current_byte" do |config|
+      config.no_width = true
+      config.output   = output
+      config.total    = 1_048_577
+    end
+
+    progress.advance(1)
+    progress.advance(1_048_574)
+    progress.advance(1)
+    progress.advance(1)
+
+    output.rewind
+
+    expect(output.read).to eq([
+      "\e[1G1B",
+      "\e[1G1024.00KB", # must not pad, line is longer
+      "\e[1G1.00MB   ", # must pad out "0KB"
+      "\e[1G1.00MB",  # must not pad, line is equal
+    ].join)
+  end
+end
diff --git a/spec/unit/resize_spec.rb b/spec/unit/resize_spec.rb
index 87f4462..f590b24 100644
--- a/spec/unit/resize_spec.rb
+++ b/spec/unit/resize_spec.rb
@@ -11,7 +11,7 @@
       "\e[1G[==        ]",
       "\e[1G[====      ]",
       "\e[0m\e[2K\e[1G",
-      "\e[1G[===  ]",
+      "\e[1G[===  ]     ",
       "\e[1G[==== ]",
       "\e[1G[=====]\n"
     ].join)